Search

This study aimed to assess the growth of spoilage bacteria in Brazilian vacuum-packed beef across different pH ranges (5.4–5.8, 5.8–6.1, ≥6.1) stored at temperatures of 0 °C, 4 °C, and 7 °C. Additionally, the research sought to identify predominant spoilage bacteria at the genus level using 16S rDNA gene sequencing and analyze the principal volatile organic compounds (VOCs) produced by this microbiota through HS-SPME/GC–MS. Lactic acid bacteria (LAB) consistently exhibited counts exceeding 6.0 Log CFU/g, regardless of temperature and pH conditions. The bacterial diversity in the meat samples reflected the influence of slaughterhouse environments, with Pseudomonas and Serratia remaining dominant across different cuts and pH levels. Post-storage, variations in pH and temperature modulated the initial bacterial diversity, leading to a reduction in diversity and an increase in LAB such as Lactobacillus , Lactococcus , Leuconostoc , and Carnobacterium. Notably, these changes were observed within pH ranges of 5.4–5.8 and 5.8–6.1, irrespective of beef cuts and storage temperatures. Based on high throughput sequencing and VOCS, correlation analysis revealed a relationship between the growth of specific spoilage microorganisms under vacuum conditions and the presence of VOCs such as alcohols (e.g., 1-propanol, 2-methyl-) and ketones (e.g., 2-nonanone, 2-octanone, 2-heptanone), identifying them as potential indicators of spoilage bacteria growth. • Spoilage bacteria growth in vacuum-packed beef with different pH and at temperature • Higher initial pH led to faster spoilage rates and reduced microbial diversity. • VOCs such as 1-propanol and 2-nonanone identified as spoilage indicators. • VOCs correlated with spoilage microorganisms for real-time quality monitoring. • Findings support strategies to enhance extend vacuum-packed beef shelf-life. [ABSTRACT FROM AUTHOR]

The burden of foodborne disease due to the consumption of animal-sourced foods is substantial in low- and middle-income countries (LMICs). Open air markets, while providing fresh and affordable foods, often have unhygienic practices that may contribute to contamination during the slaughter and processing of chicken meat. This study examines whether and how the common practice of rinse water (stored water used for rinsing broiler carcasses during processing) reuse leads to accumulation of pathogens, with potential cross contamination of chicken meat. To assess the accumulation of Campylobacter jejuni/coli, Salmonella spp., and the indicator of fecal contamination, Escherichia coli, in rinse water used during the slaughtering process at open air food markets in Maputo, Mozambique. We conducted a time-series study at three open air food markets. In a first experiment, we collected paired rinse water (N = 70), water used for chicken processing, and broiler chicken carcass (N = 60) samples from 10 vendors at 75-min intervals starting prior to any processing activity. In a second experiment, we collected 100, 50 mL rinse water samples, immediately before and after processing, from 10 vendors. Chicken processing activity and associated hygiene practices were captured through direct observation. Vendors processed 24 chickens per day, on average. In the first experiment, C. jejuni/coli and E. coli were detected in 30 % and 80 % of rinse water samples, respectively, prior to processing (baseline), and no Salmonella was detected. After the first carcass rinse, C. jejuni/coli and E. coli were detected in 100 % of samples, and Salmonella spp. was detected in 42 % of rinse water samples and 48 % of carcass samples. C. jejuni/coli showed an average 0.1 log 10 copies (95 % CI 0.0, 0.2) increase in rinse water and carcass samples every 75 min. In the second experiment, no C. jejuni/coli or Salmonella spp. were detected in baseline rinse water samples, and E. coli were detected in 78 % of baseline rinse water samples. After processing the first carcass, C. jejuni/coli were detected in 100 % of remaining samples, Salmonella spp. were detected in 28 % of pre-final rinse and 36 % of post-final rinse samples, and E. coli were detected in 81 % of pre-final rinse and 100 % of post-final rinse samples. Our results reveal that consumers are at a high risk of purchasing chicken meat contaminated with human enteropathogens. Once contaminated, rinse water stays contaminated throughout the day. Low-cost and feasible interventions implemented at the carcass wash step are needed to reduce microbial hazards on chicken meat before purchase., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The aim of this study was to determine the relative contributions of various potential food sources of human listeriosis and to identify source-specific risk factors, at exposure level, for human Listeria monocytogenes (Lm) infection. To achieve this, available Lm isolates from human cases (n = 756) and food/animal sources (n = 950) from national surveillance systems in the Netherlands (2010-2020) were whole genome sequenced. Additionally, questionnaire-based exposure data for human cases was collected. Source attribution analysis was performed using a Random Forest model based on core-genome multilocus sequence typing (cgMLST). Risk factors for human Lm infection of cattle, chicken and seafood origin were determined using beta regression analysis on the cgMLST-based attribution estimates. Results indicated that the 756 human Lm isolates were mainly attributed to cattle (62.3 %), chicken (19.4 %), and seafood (16.9 %). Specifically, fresh meat (86.2 %), including fresh bovine meat (43.7 %) and fresh chicken meat (39.3 %), accounted for most cases. These attributions stemmed from Lm contamination of either the food products or their production environments. Consumption of steak tartare and smoked salmon was associated with an increased risk of human Lm infections attributed to cattle and seafood, respectively, while no specific risk factors for chicken-borne listeriosis were identified. This study indicated that Lm isolates of cattle origin, particularly those from fresh bovine meat and associated production environments, are estimated to be the primary cause of human listeriosis in the Netherlands. This aligns with several other European source attribution studies on Lm. Moreover, the identified risk factors for human Lm infection from cattle (i.e. steak tartare) and seafood (i.e. smoked salmon) clearly indicated their attributable sources. This joint analysis of core genome and epidemiological data provided novel insights into the origins and transmission pathways of human listeriosis., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Animal food products are important sources of zoonotic agents, increasing the risk of exposure to antibiotic-resistant bacteria from farm to fork. Therefore, we aimed to detect and fully characterise Extended-Spectrum Beta-Lactamase (ESBL)-producing E. coli from the poultry sector in a One Health approach. From December 2021 to March 2022, 48 chicken meat samples were collected from 16 establishments in La Rioja (Northern Spain). Antibiotic susceptibility testing was assessed by the disk-diffusion method. Forty E. coli isolates were recovered from 33 of the 48 chicken meat samples tested (68.8%) when plated on MacConkey-agar. In addition, six ESBL-E. coli (6/48, 12.5%) were obtained on cefotaxime-supplemented MacConkey-agar, which were Whole-Genome Sequenced. A large diversity of clones and ESBL genes was observed, namely ST1140-E/bla CTX-M-32 (n = 1), ST752-A/bla TEM-52 (n = 1), ST117-B2/bla CTX-M-1 /bla SHV-12 (n = 2), ST10-A/bla SHV-12 (n = 1) and ST223-B1/bla SHV-12 (n = 1). Three IncI1-plasmids (pST3-CC3) were found carrying the bla SHV-12 /bla CTX-M-1 /bla CTX-M-32 genes in two genetic environments: i) IS26-smc-glpR-bla SHV-12 -IS26; and ii) wbuC-bla CTX-M-32 /bla CTX-M-1 -ISEcp1. The bla TEM-52 gene was carried on a P1-like phage-plasmid flanked by an IS4-mediated composite transposon. An IncHI2 plasmid harboured a bla SHV-12 gene flanked by an IS26-mediated composite transposon but also additional genes conferring resistance to aminoglycosides, chloramphenicol, and sulphonamides. To analyse the cross-sectoral relatedness of our ESBL-E. coli isolates, our six genomes were mapped with publicly available genomes (n = 2588) related to the STs detected, revealing that one of our genomes (X3078-ST117) displayed strong similarities (34-40 allelic differences) with few genomes belonging to ST117 from the poultry sector from Germany and USA. This study demonstrated that the proportion of ESBL-E. coli is still high in chicken meat in Spain. In addition, the ST117 clone and the IncI1-bla CTX-M-1-32 /bla SHV-12 plasmids might represent successful clones and plasmids adapted to the chicken host., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Yersinia enterocolitica is an important foodborne pathogen that can cause a zoonotic disease known as yersiniosis, which causes symptoms such as acute diarrhea, mesenteric adenitis, terminal ileum inflammation, pseudo appendicitis, sepsis, and other complications. The mechanism of biofilm formation in Y. enterocolitica remains poorly understood, with limited research available on this topic. This study systematically examined the distribution characteristics and biofilm formation ability of Y. enterocolitica isolated from poultry and livestock related samples. Analysis of food samples collected indicated significant presence of Y. enterocolitica (207/670, 30.9 %), particularly in frozen duck meat (7/11, 63.6 %). Majority of the isolated strains did not demonstrate biofilm-forming ability (52.7 %), while a notable percentage exhibited moderate (6.8 %) to strong (11.6 %) biofilm-forming ability. Additionally, a significant percentage of strains (16/207, 7.7 %) displayed extremely high optical density/cut-off OD (OD/ODC) ratios (the average OD value of each sample divided by the average OD value of the negative controls of each 96-well plate plus 3 standard deviations) (exceeding 10). Time-course analysis of biofilm formation in 10 isolates revealed three distinct patterns: (i) rapid increase from 6 h to 12 h, with gradual peak between 48 and 72 h followed by a slight decline and stabilization; (ii) little biofilm formation at 24 h with a gradual increase up to 96 h, maintaining this level until 120 h; and (iii) complete absence of biofilm formation throughout the experiment. Subsequent examination of differentially expressed genes (DEGs) in planktonic cells and biofilms of two strains with distinct biofilm formation capabilities identified seven metabolic pathways, including ribosome, photosynthesis, fatty acid degradation, valine, leucine, and isoleucine degradation, as well as pinene, camphor, and geraniol degradation. Significantly elevated expression levels of genes associated with flagellar assembly, bacterial chemotaxis, and quorum sensing (partially) were observed exclusively in planktonic cells of the selected strain with stronger biofilm-forming ability, implying that the heightened expression of flagellar assembly and bacterial chemotaxis-related genes is an important but not sole determinant of biofilm formation. The study contributes to the elucidation of the underlying mechanisms governing biofilm formation in Y. enterocolitica and may offer valuable insights for the advancement of novel food safety strategies., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

This study was conducted to investigate the morphological, thermal, mechanical, FTIR, physicochemical (thickness, humidity, solubility in water and water vapor permeability) and antimicrobial properties of polylactic acid film (PLA) containing hybrid graphene oxide‑zinc oxide (GO-ZnO: 1.5 % w/v) and Mentha longifolia essential oil (ML:1 % v/v) on chicken fillet kept in the refrigerator. The studied groups were microbially (total count of mesophilic aerobic bacteria, psychrotrophic bacteria, Enterobacteriaceae, Staphylococcus aureus, and lactic acid bacteria), chemically (pH, TVB-N) and sensory (color, odor, and taste) evaluated at 8-day interval (0, 2, 5 and 8). In the examination of the morphological characteristics, the PLA film had a smooth and uniform surface and the addition of ML essential oil created a discontinuous structure and the addition of GO-ZnO led to the production of a denser and more homogeneous film. The presence of GO-ZnO increased the thickness, decreased moisture content and solubility in water, and added ML essential oil increased moisture content and decreased solubility in water (p˂0.05). The results of the mechanical evaluation showed that the addition of ML essential oil and GO-ZnO reduced elongation at break and tensile strength (p˂0.05). The addition of ML essential oil increased the thermal resistance and the addition of GO-ZnO decreased the thermal resistance compared to the film containing ML essential oil. The antimicrobial effect of films containing ML essential oil was confirmed in this study (p˂0.05). The addition of GO-ZnO did not change the count of any of the microbial groups. TVB-N showed that groups containing ML essential oil had lower levels of volatile nitrogenous bases than the control group (p˂0.05). Sensory evaluation of the studied groups showed that chicken fillets packed with films containing ML essential oil had the highest score in terms of color, smell and taste. The results of the present study showed that PLA film containing GO-ZnO and ML essential oil can be used to increase the shelf life and maintain the sensory characteristics of chicken fillets, and it can be used as a suitable packaging to increase the shelf life of food products., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this article., (Copyright © 2024. Published by Elsevier B.V.)

LED technology has emerged as a promising non-thermal preservation method for highly perishable muscle foods like meat and fish. Muscle foods are most susceptible to spoilage due to their high moisture content and nutrient density, which create an ideal environment for microbial growth, chemical oxidation, and enzymatic activity, which negatively alter their quality. LED treatment offers an effective solution by significantly reducing microbial loads and extending shelf life without adversely affecting sensory and nutritional properties. Specific wavelengths of LED light induce microbial inactivation through mechanisms like DNA damage, lipid oxidation, and protein alteration. Studies have shown that LED treatment can preserve the fresh-like quality of muscle foods by mitigating common spoilage processes. The advantages of LED technology include its non-thermal nature, ability to integrate with other preservation methods, and controllability in terms of intensity and wavelength. This enables for tailored applications based on food type and spoilage risks. As consumer demand grows for safe, chemical-free food options, LED technology addresses this need while enhancing food safety and quality. Further research is encouraged to optimize LED applications in various muscle food preservation contexts. With its exceptional ability to produce DNA damage in bacteria, inactivate enzymes, and malfunction biological activities, LED could serve as an inexpensive processing intervention to safeguard the quality of meat and seafood products. This review underscores the potential of LED technology as a promising alternative to traditional preservation methods for decontamination of muscle food., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Using a solvent-casting method, a poly(lactic acid) (PLA) film incorporated with caprylic acid (CA) was developed as an active packaging against Salmonella enterica ser. Typhimurium and S. enteritidis to reduce the risk of microbial contamination during distribution and storage of meat. According to the minimum inhibitory concentration (MIC) test results of the natural antimicrobial, CA was introduced at 0.6, 1.2, 2.4, and 4.8 % (v/v) into neat PLA. The biofilm inhibitory effect and antimicrobial efficacy of CA-PLA film against both Salmonella strains, as well as the intermolecular interactions and barrier properties of CA-PLA film, were evaluated. Biofilm formation was reduced to below the detection limit (<1.0 log CFU/cm 2 ) for both S. typhimurium and S. enteritidis when co-cultured overnight with 4.8 % CA-PLA film. The 4.8 % CA-PLA film achieved maximum log reductions of 2.58 and 1.65 CFU/g for S. typhimurium and 2.59 and 1.76 CFU/g for S. enteritidis on inoculated chicken breast and beef stored at 25 °C overnight, respectively, without any quality (color and texture) losses. CA maintained its typical chemical structure in the film, as confirmed by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectra. Furthermore, film surface morphology observations by field emission scanning electron microscopy (FESEM) showed that CA-PLA film was smoother than neat PLA film. No significant (P > 0.05) changes were observed for water vapor permeability and oxygen permeability by the addition of CA into PLA film, suggesting that CA-PLA film is a promising strategy for active packaging to control Salmonella contamination in the meat industry., Competing Interests: Declaration of competing interest No potential conflict of interest was reported by the authors., (Copyright © 2024. Published by Elsevier B.V.)

The aim of the study was to analyse the key microbial contaminants of plant-based meat analogues (PBMA) from retail. A total of 43 samples of PBMAs (12 frozen/31 chilled) in the "ready-to-cook" category, such as hamburgers, meatballs or breaded imitation steaks were purchased in retail stores in the Czech Republic in summer (n = 21) and autumn 2022 (n = 22). The detected indicator bacteria (total viable count, lactic acid bacteria, Enterobacteriaceae, yeasts, moulds) had relatively low values in the analysed PBMA samples and only rarely reached levels of 7 log CFU/g. E. coli, STEC and coagulase-positive staphylococci were not detected by isolation from plates in any of analysed samples. Mannitol positive Bacillus spp. were isolated from almost half of the analysed samples of the PBMA. B. cereus sensu lato was isolated from 3 samples by isolation from plates, and after enrichment in 35 samples (81 %). Clostridium perfringens could not be detected by isolation from plates, nevertheless after multiplication, it was detected in 21 % of samples. Analyses of PBMA samples revealed considerable variability in microbial quality. The presence of spore-forming bacteria with the potential to cause foodborne diseases is alarming. However, to evaluate the risks, further research focused on the possibilities of growth under different conditions of culinary treatment and preservation is needed., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The emergence of carbapenem-resistant bacteria especially carbapenem-resistant Escherichia coli (CREC) in food animals poses a serious threat to food safety and public health. Reports about the dissemination of carbapenem-resistant bacteria along the food animal production chain are scattered and mainly focus on swine and chicken. Abuse of antibiotics in duck farms is common especially in China which has the largest duck production industry, however, the CREC transmission between farmed ducks and slaughtered meats remains unclear and the role of slaughterhouse in disseminating CREC among duck meats remains largely unknown. Herein, we collected 251 fecal samples from five typical duck farms along with 125 slaughtered meat samples (25 from each farm) in the corresponding slaughterhouse in Anhui Province, China, in December 2018. All samples were screened for CREC isolates which were analyzed for the presence of carbapenemase genes and colistin resistance gene mcr. The resistance profiles, transferability, pulsed-field gel electrophoresis (PFGE), whole-genome sequencing and phylogenetic analysis of the CREC isolates from both ducks and meats were further characterized. This is the first report presenting the high prevalence of bla NDM -positive CREC isolates in ducks from duck farms (57.8 %) and slaughtered meats (33.6 %) in the corresponding slaughterhouse. Among the 203 bla NDM -positive CREC isolates obtained in this study, 19.2 % harbored mcr-1 and all CREC isolates showed resistance to nearly all currently available antibiotics (except tigecycline). Of note, mcr-1 was found in 17.8 % of the meat-derived CREC carrying bla NDM . Based on the PFGE analysis, clonal spread of bla NDM -positive CREC including some also carrying mcr-1 was found between farmed ducks and slaughtered duck meats even from different farms. Special attention should be paid to the clonal dissemination of meat-derived CREC within the slaughterhouse, which contributed to the high prevalence of bla NDM in slaughtered meats. Additionally, horizontal transmission mainly mediated by transferable bla NDM-5 -bearing IncX3 plasmids, untypable bla NDM-1 -bearing plasmids and mcr-1-bearing IncHI2 plasmids further facilitated the rapid spread of such multidrug-resistant strains. Notably, the bla NDM -bearing plasmids and mcr-1-bearing plasmids in CREC from meats were highly similar to those from animals and humans. More worryingly, the phylogenomic analysis showed that CREC isolates from both ducks and corresponding meats clustered with previously reported human CREC isolates carrying mcr-1 in different geographical areas including China. These findings further prove that the CREC and resistance plasmids in farmed ducks could transmit to meats even from different farms via the slaughterhouse and then trigger infections in humans. The high prevalence and clonal transmission of CREC isolates including those also carrying mcr-1 between ducks and meats are alarming, and urgent control measures are required to reduce the dissemination of such organisms., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The aim of this study was to characterize the pulp of Rheum ribes L. and to determine the effect of the pulp enriched with eugenol (1 %) or thymol (1 %) on the microbiological and physico-chemical quality of chicken breast fillets. Chicken breast fillets, inoculated with Listeria monocytogenes, Salmonella enterica subsp. enterica serovar Typhimurium, and Escherichia coli O157:H7 (~6.0 log 10 ), were marinated for 24 h in a mixture prepared from a combination of Rheum ribes L. pulp with eugenol or thymol. The quality parameters were analyzed for 15 days at +4 °C. The Rheum ribes L. pulp was found to have high antioxidant activity, high total phenolic content and contained 22 different phenolic substances, among which rutin ranked first. The pulp contained high levels of p-xylene and o-xylene as volatile substances and citric acid as an organic acid. The combination of Pulp + Eugenol + Thymol (PET) reduced the number of pathogens in chicken breast fillets by 2.03 to 3.50 log 10 on day 0 and by 2.25 to 4.21 log 10 on day 15, compared to the control group (P < 0.05). The marinating treatment significantly lowered the pH values of fillet samples on the first day of the study, compared to the control group (P < 0.05). During storage, TVB-N levels showed slower increase in the treatment groups compared to the control group (P < 0.05). In addition, the marinating process led to significant changes in physicochemical parameters such as water holding capacity, color, texture, cooking loss, and drip loss compared to the control group (P < 0.05). In conclusion, the results of this study showed that the pulp of Rheum ribes L., which has a high antioxidant capacity and contains various bioactive compounds. Furthermore, S. Typhimurium, E. coli O157:H7 and L. monocytogenes were inhibited considerably by marinating Rheum ribes L. pulp with a combination of eugenol and thymol., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Non-typhoidal Salmonella represents a significant global concern for food safety and One Health. Despite the United Arab Emirates (UAE) being a leading consumer of chicken meat globally, there is a lack of comprehensive understanding regarding the prevalence and genomic characteristics of Salmonella within the country. This study aims to address this gap by conducting a thorough analysis of Salmonella prevalence, antimicrobial resistance, and genomic profiles of isolates obtained from whole broiler carcasses retailed under chilled conditions in the UAE. Our findings reveal that Salmonella was detected in 41.2 % (130/315) of the sampled chilled broiler carcasses, with notable variability observed among samples sourced from six different companies. Phenotypic antimicrobial resistance (AMR) testing, among 105 isolates, highlighted high resistance rates to tetracycline (97.1 %), nalidixic acid (93.3 %), ampicillin (92.4 %), azithromycin (75.2 %), ciprofloxacin (63.8 %), and ceftriaxone (54.3 %). Furthermore, a concerning 99 % (104/105) of the isolates exhibited multidrug resistance. Whole-genome sequencing (WGS) of 60 isolates identified five serovars, with S. infantis/Sequence Type (ST) 32 (55 %) and S. Minnesota/ST-458 (28.3 %) being the most prevalent. WGS analysis unveiled 34 genes associated with antimicrobial resistance, including mcr-1.1 (only in two isolates), conferring resistance to colistin. The two major serovars, Infantis and Minnesota, exhibited significant variation (P-values <0.001) in the distribution of major AMR genes (aadA1, bla CMY-2 , bla SHV-12 , qnrB19, qnrS1, sul1, and sul2). Notably, the gene qacEdelta, conferring resistance to quaternary ammonium compounds commonly found in disinfectants, was universally present in all S. Infantis isolates (n = 33), compared to only one S. Minnesota isolate. Additionally, all S. Infantis isolates harbored the IncFIB (pN55391) plasmid replicon type. Major serovars exhibited distinct distributions of antimicrobial resistance genes, underscoring the importance of serovar-specific surveillance. These findings emphasize the critical need for continuous surveillance and intervention measures to address Salmonella contamination risks in poultry products, providing valuable insights for public health and regulatory strategies not only in the UAE but also globally., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Foodborne illnesses, caused by harmful microorganisms in food, are a significant global health issue. Current methods for identifying these pathogens are both labor-intensive and time-consuming. In this research, we devised a swift and precise detection technique using recombinase polymerase amplification combined with a lateral flow dipstick (RPA-LFD) for three foodborne pathogens found in meat. By employing a dedicated detection device, RPA-LFD allows for the rapid analysis of DNA from Escherichia coli O157 (E. coli O157), Salmonella, and Shigella-pathogens that are prohibited in food. The detection thresholds for E. coli O157, Salmonella, and Shigella are 0.168 fg/μl (1.04 CFU/ml), 0.72 fg/μl (27.49 CFU/ml), and 1.25 fg/μl (48.84 CFU/ml), respectively. This method provides a short detection window, operates at low temperatures, follows simple procedures, and exhibits high sensitivity. Our study establishes the RPA-LFD method for simultaneously identifying the nucleic acid of three foodborne pathogens, offering an efficient solution for quickly identifying multiple contaminants., Competing Interests: Declaration of competing interest No conflict of interest exits in the submission of this manu, and manu is approved by all authors for publication. I would like to declare on behalf of my co-authors that the work described was original research that has not been published previously, and not under consideration for publication elsewhere, in whole or in part. All the authors listed have approved the manu that is enclosed., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Lactic acid bacteria (LAB) are frequently used in meat fermentation, and mixed stater cultures are reported to perform better than single ones. Lactiplantibacillus plantarum 3-19 and Pediococcus pentosaceus 18-1 were chosen from 28 sour-meat-origin strains to examine the effects of single and combined inoculation on sour meat quality. Natural fermentation was used as a control to investigate changes in pH, water activity (a w ), amino acid nitrogen (AN), texture, microbial diversity, and volatile organic compounds (VOCs) during fermentation. The pH and a w of each inoculation group were significantly decreased, and AN content was significantly increased. The inoculation of P. pentosaceus 18-1 significantly reduced putrescine, cadaverine, and tryptamine content (p < 0.05), while the inoculation of Lpb. plantarum 3-19 significantly reduced cadaverine amounts (p < 0.05). At the fermentation endpoint, the total biogenic amines content in the C group was 992.96 ± 14.07, which was 1.65, 2.57, and 3.07 times higher than that in the Lp, Pe, and M groups, respectively. The mixed inoculation group combined the advantages of both strains and decreased total biogenic amines most significantly. At the end of fermentation, the VOCs in C, Lp, Pe, and M groups were 10.11, 11.56, 12.45, and 13.39 times higher than those at the beginning of fermentation. Inoculation promoted the production of key VOCs (OAV > 2000) such as heptanal, octanal, and (E)-2-nonanal. The mixed inoculation group had the highest variety and content of VOCs and the highest content of the above key VOCs, significantly enhancing its fruity, floral, ester, and other aromas. Sensory evaluation indicated that the M group had the best overall acceptability. Finally, it was suggested that a combination of Lpb. plantarum 3-19 and P. pentosaceus 18-1 is a novel and efficient starter culture for processing sour meat since they lower the amounts of biogenic amines in the meat and promote the production of VOCs., Competing Interests: Declaration of competing interest The authors confirm that they have no conflicts of interest with respect to the work described in this manuscript., (Copyright © 2024. Published by Elsevier B.V.)

Antimicrobial resistance (AMR) is a global emerging problem for food safety and public health. Retail meat is one of the vehicles that may transmit antimicrobial resistant bacteria to humans. Here we assessed the phenotypic and genotypic resistance of non-typhoidal Salmonella from retail meat collected in California in 2019 by the National Antimicrobial Resistance Monitoring System (NARMS) Retail Food Surveillance program. A total of 849 fresh meat samples were collected from randomly selected grocery stores in Northern and Southern California from January to December 2019. The overall prevalence of Salmonella was 15.31 %, with a significantly higher occurrence in Southern (28.38%) than in Northern (5.22 %) California. The prevalence of Salmonella in chicken (24.01 %) was higher (p < 0.001) compared to ground turkey (5.42 %) and pork (3.08 %) samples. No Salmonella were recovered from ground beef samples. The prevalence of Salmonella in meat with reduced antibiotic claim (20.35 %) was higher (p < 0.001) than that with conventional production (11.96 %). Salmonella isolates were classified into 25 serotypes with S. Kentucky (47.73 %), S. typhimurium (11.36 %), and S. Alachua (7.58 %) as predominant serotypes. Thirty-two out of 132 (24.24 %) Salmonella isolates were susceptible to all tested antimicrobial drugs, while 75.76 % were resistant to one or more drugs, 62.88 % to two or more drugs, and 9.85 % to three or more drugs. Antimicrobials that Salmonella exhibited high resistance to were tetracycline (82/132, 62.12 %) and streptomycin (79/132, 59.85 %). No significant difference was observed between reduced antibiotic claim and conventional production in the occurrence of single and multidrug resistance. A total of 23 resistant genes, a D87Y mutation of gyrA, and 23 plasmid replicons were identified from resistant Salmonella isolates. Genotypic and phenotypic results were well correlated with an overall sensitivity of 96.85 %. S. infantis was the most resistant serotype which also harbored the IncFIB (pN55391) plasmid replicon and gyrA (87) mutation. Data from Northern and Southern California in this study helps us to understand the AMR trends in Salmonella from retail meat sold in the highly populous and demographically diverse state of California., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Lactococcus (Lc.) paracarnosus and the phylogenetically closely related Lc. carnosus species are common members of the microbiota in meat stored under modified atmosphere and at low temperature. The effect of these strains on meat spoilage is controversially discussed. While some strains are known to cause spoilage, others are being studied for their potential to suppress the growth of spoilage and pathogenic bacteria. In this study, Lc. paracarnosus DSM 111017 T was selected based on a previous study for its ability to suppress the growth of meat spoilers, including Brochothrix thermosphacta. The mechanism by which this bioprotective strain inhibits competing bacteria and how it contributes to spoilage are not yet known. To answer these two questions, we investigated the effect of four different headspace gas mixtures (simulated air (21 % O 2 /79 % N 2 ); HiOx-MAP (70 % O 2 /30 % CO 2 ); nonOx-MAP (70 % N 2 / 30 % CO 2 ); simulated vacuum (100 % N 2 ) and the presence of Brochothrix (B.) thermosphacta TMW 2.2101 on the growth and transcriptional response of Lc. paracarnosus DSM 111017 T when cultured on a meat simulation agar surface at 4 °C. Analysis of genes specifically upregulated by the gas mixtures used revealed metabolic pathways that may lead to different levels of spoilage metabolites production. We propose that under elevated oxygen levels, Lc. paracarnosus preferentially converts pyruvate from glucose and glycerol to uncharged acetoin/diacetyl instead of lactate to counteract acid stress. Due to the potential production of a buttery off-flavour, the strain may not be suitable as a protective culture in meat packaged under high‑oxygen conditions. 70 % N 2 / 30 % CO 2 , simulated vacuum- and the presence of Lc. paracarnosus inhibited the growth of B. thermosphacta TMW 2.2101. However, B. thermosphacta did not affect gene regulation of metabolic pathways in Lc. paracarnosus, and genes previously predicted to be involved in B. thermosphacta growth suppression were not regulated at the transcriptional level. In conclusion, the study indicates that the gas mixture used in packaging significantly affects the metabolism and spoilage potential of Lc. paracarnosus and its ability to inhibit B. thermosphacta growth., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Victoria Werum reports financial support was provided by German Federal Ministry of Food and Agriculture. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

This study investigates the possibility of utilizing drip as a non-destructive method for assessing the freshness and spoilage of chicken meat. The quality parameters [pH, volatile base nitrogen (VBN), and total aerobic bacterial counts (TAB)] of chicken meat were evaluated over a 13-day storage period in vacuum packaging at 4 °C. Simultaneously, the metabolites in the chicken meat and its drip were measured by nuclear magnetic resonance. Correlation (Pearson's and Spearman's rank) and pathway analyses were conducted to select the metabolites for model training. Binary logistic regression (model 1 and model 2) and multiple linear regression models (model 3-1 and model 3-2) were trained using selected metabolites, and their performance was evaluated using receiver operating characteristic (ROC) curves. As a result, the chicken meat was spoiled after 7 days of storage, exceeding 20 mg/100 g VBN and 5.7 log CFU/g TAB. The correlation analysis identified one organic acid, eight free amino acids, and five nucleic acids as highly correlated with chicken meat and its drip during storage. Pathway analysis revealed tyrosine and purine metabolism as metabolic pathways highly correlated with spoilage. Based on these findings, specific metabolites were selected for model training: ATP, glutamine, hypoxanthine, IMP, tyrosine, and tyramine. To predict the freshness and spoilage of chicken meat, model 1, trained using tyramine, ATP, tyrosine, and IMP from chicken meat, achieved a 99.9 % accuracy and had an ROC value of 0.884 when validated using drip metabolites. This model 1 was improved by training with tyramine and IMP from both chicken meat and its drip (model 2), which increased the ROC value for drip metabolites from 0.884 to 0.997. Finally, selected two metabolites (tyramine and IMP) can predict TAB and VBN quantitatively through models 3-1 and 3-2, respectively. Therefore, the model developed using metabolic changes in drip demonstrated the capability to non-destructively predict the freshness and spoilage of chicken meat at 4 °C. To make generic predictions, it is necessary to expand the model's applicability to various conditions, such as different temperatures, and validate its performance across multiple chicken batches., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Listeria monocytogenes is a foodborne pathogen that can cause deadly severe listeriosis. While systematic review and meta-analysis are powerful tools for comprehensive analysis by pooling every related study, these approaches to L.monocytogenes contamination food have yet to be studied in South Korea. We aimed to identify high-risk L.monocytogenes foods in South Korea through a prevalence survey of retail food products for the first time. A total of 13,684 samples of 59 articles were used for meta-analysis through the systematic review, and the results were synthesized using a random-effects model considering the heterogeneity. The overall pooled prevalence was 2.26 % (95 % CI: 1.44-3.52 %). Among nine food categories, meat exhibited the highest prevalence at 8.32 % (95 % CI: 4.42-12.14 %) after sample size restriction. Specifically, a post-hoc sensitivity analysis was conducted to identify the prevalence difference among subgroups and the source of heterogeneity. Intriguingly, the analysis revealed chicken as the primary contributor to the elevated prevalence of L.monocytogenes, a key factor deriving the observed heterogeneity. This study carries significant implications for public health and food safety in Korea. Furthermore, knowledge of differences in prevalence levels in various foods will be able to be used as a predictive guideline for foodborne outbreaks., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Ok Kyung Koo reports financial support was provided by National Research Foundation of Korea. Ok Kyung Koo reports financial support was provided by Chungnam National University., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Microbial survival of heating and cross-contamination are the two transmission routes during food preparation in the consumers' kitchen that are relevant for QMRA (Quantitative Microbial Risk Assessment). The aim of the present study was to extend the limited amount of data on microbial survival during real-life preparation of meat and meat products and to obtain accessory temperature data that allow for a more general (product unspecific) approach. Therefore survival data were combined with extensive measurements of time- and location dependent temperature using an infrared camera for the surface and buttons for the inside of the product, supplemented with interpolation modelling. We investigated the survival of heating of Escherichia coli O111:H2 in beefsteak, hamburgers (beef and 50% beef 50% pork (HH)), meatballs (beef and HH) and crumbs (HH). For beefsteak, survival as a whole is dominated by the sides, giving a log reduction of 1–2 (rare), 3–4 (medium) and 6–7 (done). Limited measurements indicated that done preparation gave 5–6 log reduction for crumbs and at least 8–9 log for the other products. Medium preparation gave a higher reduction in hamburgers (2–4 log) than in meatballs (1–2 log) and in beef (3–4) than in HH (2–3) hamburgers. In general, our 'done' results give larger inactivation than found in literature, whereas 'rare' and 'medium' results are similar. The experiments resulted in two types of curves of D 70 /z-values, dependent on product, doneness and for beefsteaks sides vs. top/bottom. One type of curve agrees reasonably with literature D 70 /z estimates from isothermal temperature experiments, which supports using these estimates for home style cooking QMRA calculations. In case of the other type of curve, which is mainly found for (near) surface contamination in close contact with the pan, these literature estimates cannot be applied. We also applied a simplified approach, assuming thermal inactivation is dominated by the highest temperatures reached. The time duration of this highest temperature gives accessory D-values which prove to fit with isothermal temperature literature data, thus suggesting application of such data for QMRA is possible by this approach also, which is less labor intensive both in terms of measurements and modelling. In real life, variability in product properties and preparation styles is large. Further studies are needed to analyze the effect on survival, preferably focusing on determining the essential variables. More variation in heating time will allow for estimating D 70 /z point estimates rather than curves representing possible sets of D 70 /z-values. • Survival of E. coli and temperature of meat were studied at home frying conditions. • We studied beefsteak, hamburgers, meat balls and crumbs. • Inactivation was from 1 to 2 log (rare beefsteak) to at least 8–9 log (done products). • Results from D/z- and simplified analysis partly agree with isothermal literature. • Isothermal data can therefore support the estimation of survival after home frying. [ABSTRACT FROM AUTHOR]

Shiga toxin-producing Escherichia coli (STEC) is a major cause of foodborne illness, ranging from mild diarrhea to permanent kidney failure. This study summarizes the results of four surveys performed at different time periods, which investigated the occurrence and characteristics of STEC in beef, lamb and leafy greens available in the Swedish retail market. Such data is required when assessing the public health risk of varying types of STEC in different foods, and for establishing risk management measures. Samples from domestic and imported products were collected based on their availability in the retail market. The occurrence of STEC was investigated in 477 samples of beef, 330 samples of lamb and 630 samples of leafy greens. The detection of virulence genes (stx 1 , stx 2 , eae) was performed using real-time PCR followed by the isolation of bacteria from stx-positive enriched samples using immunomagnetic separation or an immunoblotting method. All STEC isolated from the food samples was further characterised in terms of stx subtyping and serotyping through whole genome sequencing. STEC was isolated from 2 to 14 % of beef samples and 20 to 61 % of lamb samples, depending on the region of origin. STEC was not isolated from samples of leafy greens, although stx genes were detected in 11 (2 %) of the samples tested. In total, 5 of the 151 sequenced STEC isolates from meat contained stx2 and eae, of which 4 such combinations had the stx 2a subtype. The stx 2 gene, stx 2a in particular, is strongly associated with serious disease in humans, especially in combination with the eae gene. The isolates belonged to 20 different serotypes. Two isolates from beef and one from lamb belonged to the serotype O157:H7 and contained genes for stx 2 and eae. Overall, several combinations of stx subtypes were found in isolates from beef, whereas stx 1c , either alone or together with stx 2b , was the dominant combination found in STEC from lamb. In conclusion, STEC was rare in whole meat samples of domestic beef in the Swedish retail market, whereas such bacteria were frequently found in minced meat and whole meat samples of imported beef and domestic and imported lamb. Although the number of isolates containing genes linked to an increased risk of severe disease was low, beef and lamb in the Swedish retail market is a common source of human exposure to potentially pathogenic STEC., Competing Interests: Declaration of competing interest None., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

Traditional pork value chains dominate the production and distribution of pork in Vietnam; however, the high level of microbiological contamination in pork may increase the risk of food-borne disease for consumers. There is limited evidence about how to feasibly and scalably reduce microbial contamination in pork sold in traditional markets. This study aimed to assess the effectiveness of light-touch interventions for changing worker behaviour in small-scale slaughterhouses and vendors at traditional pork shops, as well as to identify risk factors for pork contamination. The intervention packages consisted of providing hygiene tools and delivering a food safety training which had been designed in a participatory way and covered 10 small-scale slaughterhouses and 29 pork shops. Pig carcasses, retailed pork, contact surfaces, and hands were sampled to measure the total bacterial count (TBC) and Salmonella contamination before, three and six weeks after the intervention, and trainee practices were observed at the same time. Linear and generalized linear mixed effects models were constructed to identify risk factors for TBC and Salmonella contamination at the slaughterhouses and pork shops. The interventions at slaughterhouses and pork shops both showed a slight reduction of TBC contamination in pig carcasses and Salmonella prevalence in retailed pork, while the TBC in retailed pork decreased only marginally. For slaughterhouses, the regression model indicated that smoking or eating during slaughtering (indicating poor hygienic practices) was associated with TBC increasing, while cleaning floors and wearing boots reduced TBC contamination. For pork shops, using rough materials (cardboard or wood) to display pork was the only factor increasing TBC contamination in pork, whereas cleaning knives was associated with lower TBC. Besides, the presence of supporters and wearing aprons reduced the probability of Salmonella contamination in pork. The findings highlight the effectiveness of light-touch interventions in reducing microbial contamination in pig carcasses at small-scale slaughterhouses and pork at traditional shops over the study period., Competing Interests: Declaration of competing interest The authors declare they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

The advent of high-throughput sequencing technologies in recent years has revealed the unexpected presence of genus Photobacterium within the chicken meat spoilage ecosystem. This study was undertaken to decipher the occurrence, the growth patterns and the genotypic biodiversity of Photobacterium phosphoreum on chicken breast fillets stored aerobically at 4 °C through conventional microbiological methods and molecular techniques. Samples were periodically cultured on marine broth agar (MA; supplemented with meat extract and vancomycin) for the enumeration of presumptive bioluminescent Photobacterium spp. In total, 90 bioluminescent bacteria were recovered from the initial (time of first appearance), middle and end stages of storage. Concomitantly, 95 total psychrotrophic/psychrophilic bacteria were isolated from the same medium to assess the presence and diversity of non-luminous photobacteria. Genetic diversity between bioluminescent isolates was assessed with two PCR-based DNA fingerprinting methods, i.e. RAPD and rep-PCR. Moreover, the characterization of selected bacterial isolates at the genus and/or species level was performed by sequencing of the 16S rRNA and/or gyrB gene. Bioluminescent bacteria were scarcely encountered in fresh samples at population levels of ca. 2.0 log CFU/g, whilst total psychrotrophic/psychrophilic bacteria were found at levels of ca. 4.4 log CFU/g. As time proceeded and close to shelf-life end, bioluminescent bacteria were encountered at higher populations, and were found at levels of 5.3 and 7.0 log CFU/g in samples from the second and third batch, respectively. In the first batch their presence was occasional and at levels up to 3.9 log CFU/g. Accordingly, total psychrotrophic/psychrophilic bacteria exceeded 8.4 log CFU/g at the end of storage, suggesting the possible underestimation of bioluminescent populations following the specific cultivation conditions. Sequence analysis assigned bioluminescent isolates to Photobacterium phosphoreum, while genetic fingerprinting revealed high intra-species variability. Respectively, total psychrotrophs/psychrophiles were assigned to genera Pseudomonas, Shewanella, Psychrobacter, Acinetobacter, Vibrio and Photobacterium. Non-luminous photobacteria were not identified within the psychrotrophs/psychrophiles. Results of the present study reveal the intra- and inter-batch variability on the occurrence and growth responses of P. phosphoreum and highlight its potential role in the chicken meat spoilage consortium., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2023 Elsevier B.V. All rights reserved.)

This study estimates the shelf life of vacuum packed beef meat (three muscles: striploin (longissimus thoracis et lumborum, LTL), tenderloin (psoas major, PM) and outside chuck (trapezius thoracis, TT)) at refrigeration temperatures (0 °C-10 °C) based on modelling the growth of two relevant groups of spoilage microorganisms: lactic acid bacteria (LAB) and Enterobacteriaceae. The growth models were developed combining a two-step and a one-step approach. The primary modelling was used to identify the parameters affecting the growth kinetics, guiding the definition of secondary growth models. For LAB, the secondary model included the effect of temperature and initial pH on the specific growth rate. On the other hand, the model for Enterobacteriaceae incorporated the effect of temperature on the specific growth rate and the lag phase; as well as the effect of the initial pH on the specific growth rate, the lag phase and the initial microbial count. We did not observe any significant effect of the type of muscle on the growth kinetics. Once the equations were defined, the models were fitted to the complete dataset using a one-step approach. Model validation was carried out by cross-validation, mitigating the impact of an arbitrary division between training and validation sets. The models were used to estimate the shelf life of the product, based on the maximum admissible microbial concentration (7 log CFU/g for LAB, 5 log CFU/g for Enterobacteriaceae). Although LAB was the dominant microbiota, in several cases, both LAB and Enterobacteriaceae reached the critical concentration practically at the same time. Furthermore, in some scenarios, the end of shelf life would be determined by Enterobacteriaceae, pointing at the potential importance of non-dominant microorganisms for product spoilage. These results can aid in the implementation of effective control measures in the meat processing industry., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

Abstract Global widespread of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae , especially Escherichia coli poses a greater threat in healthcare and community settings of humans. Raw meats from food animals colonized with ESBL producers may be one of important transmission routes for those bacteria in the community. This study investigated the presence of ESBL-producing E. coli in retail raw chicken and pork meats in Japan. ESBL producers were detected from the 59 of 150 (39.3%) chicken samples, but none were from all the 50 pork samples tested. The bla CTX-M-14 (17; 24.3%) was most frequently identified, followed by bla CTX-M-2 (16; 22.9%), bla SHV-12 (11; 15.7%), and bla CTX-M-55 (10; 14.3%) among a total of 70 ESBL-producing E. coli isolates from 59 chicken samples. The isolates with bla CTX-M-14 were often combined with phylogroup B1 (9/17) mainly composed of ST162 (7/9), and phylogroup F (5/17) with diverse STs. The bla CTX-M-14 was basically associated with the common elements IS Ecp1 and ΔIS 903 or IS 903 in all 17 isolates. In 6 isolates, comprising 5 phylogroup B1-ST162 and a nontypeable-ST162 isolates, an IS 26 -truncated IS Ecp1 was identified upstream of the bla CTX-M-14 , and a fosA3 was further located downstream of ΔIS 903. Furthermore, some mobile genetic elements mediating bla CTX-M-14 unique to raw chicken meat portions were identified. The bla CTX-M-2 gene was preceded by IS Ecp1 or IS CR1 in 16 isolates, whereas the presence of Δ orf3 downstream of bla CTX-M-2 was limited only in 6 isolates from Brazilian samples though they exhibited diverse phylogroups and STs. The bla CTX-M-55 and bla CTX-M-1 shared classical flanking structures, IS Ecp1 - bla CTX-M - orf477 , although the length of spacer sequences between IS Ecp1 and the start codon of bla CTX-M was 45 bp and 80 bp for bla CTX-M-55 and bla CTX-M-1 , respectively. Among bla SHV-12 -harboring isolates, ST38 was frequently detected (6/11) though their phylogroup distribution varied. In conclusion, besides transmission of bla gene-harboring E. coli lineages which have adaptability to both human and chicken, spread of mobile genetic elements associated with bla genes from E. coli lineages adapted to chicken to those adapted to human is highly suggested. Our results provide important information to gain a better understanding of the transmission risk of bla genes from retail chicken meats to human. Highlights • ESBL-positive E. coli isolates were detected in 59 of 150 (39.3%) chicken samples. • 70 ESBL-producing E. coli isolates were detected from 59 chicken samples. • bla CTX-M-14 (17; 24.3%), followed by bla CTX-M-2 (16; 22.9%) were identified. • bla CTX-M-14 -harboring isolates were mostly associated with phylogroups B1-ST162. • IS 26 -ΔIS Ecp1 - bla CTX-M-14 -ΔIS 903 - fosA3 was detected in 6 ST162 isolates. [ABSTRACT FROM AUTHOR]

Coagulase-negative staphylococci are frequently isolated from meat products and two species are used as starter cultures in dry fermented sausages. In these products, they face various environmental conditions such as variation of redox potential and oxygen levels that can lead to oxidative stress. Furthermore, when nitrate and nitrite are added as curing salts, staphylococci also experience nitrosative stress. A nos gene encoding a nitric oxide synthase (NOS) is present in the genome of all staphylococci. NOS produces nitric oxide (NO) and citrulline from arginine, but its activity is still poorly characterized, particularly in coagulase-negative staphylococci. NO is highly reactive with a broad spectrum of activity resulting from targeting metal centres (heme and non-heme) and protein thiols. At low concentration, NO acts as a signalling molecule, while at higher concentration it generates stress. Thus, it was initially suggested that staphylococcal NOS counteract oxidative stress in relation to PerR and Fur regulators. In the physiology of staphylococci, it has recently been highlighted that NO controls the rate of aerobic respiration and regulates the transition from aerobic to nitrate respiration and also helps maintain the membrane potential in relation to the two-component systems SrrAB and AirRS. As NO interacts with heme centres, it binds the heme iron atom of myoglobin to form nitrosomyglobin, which is the typical red pigment of cured meat. However, the contribution of NOS to this reaction in meat products has yet to be evaluated. [ABSTRACT FROM AUTHOR]

Pomegranate juice is a product with enhanced functional properties that could be used as an alternative to traditional marination ingredients and effectively retard microbial growth along with providing an improved sensory result. In this study, two pomegranate based marinades were prepared for the marination of chicken breast fillets and the marinated samples were aerobically stored at 4 and 10 °C for 9 days. Raw, non-marinated chicken samples were used as control. Levels of total viable counts (TVC), Pseudomonas spp., Brochothrix thermosphacta , Enterobacteriaceae and lactic acid bacteria (LAB) were determined together with sensory assessment to evaluate the evolution of spoilage. The profile of organic acids and volatile compounds was also analyzed during storage. The shelf life of marinated samples was significantly extended compared to control samples at both storage temperatures (e.g., up to 5 and 6 days for the pomegranate/lemon marinated samples stored at 4 and 10 °C, respectively) as evaluated by both microbiological and sensory analyses. The profile of the organic acids and the volatilome of marinated and control samples were remarkably differentiated according to storage time, microbial load and sensory score. The findings of this study suggest that pomegranate juice could be used as a novel ingredient in marinades to improve the sensory attributes, while prolonging the shelf life of chicken meat. [ABSTRACT FROM AUTHOR]

Clostridium perfringens is a major foodborne health hazard that can cause acute gastroenteritis in consumers, and is often associated with cooked meat and poultry products. Improper cooling after cooking may allow this pathogen to grow in a product, producing an enterotoxin that causes food poisoning. This study was conducted to evaluate the effect of common ingredients, including sodium tripolyphosphate (STPP), sodium lactate (NaL), and sodium chloride (NaCl), on the germination and outgrowth of C. perfringens spores in meat products. The growth/no growth test was conducted in Shahidi Ferguson Perfringens agar mixed with STPP (0–2500 ppm), NaL (0–4%), and NaCl (0–4%) in microplates. Turbidity measurements at 600 nm were compared before and after anaerobic incubation at 46 °C to evaluate growth and no growth conditions. The dichotomous responses were analyzed by logistic regression to develop a model for estimating the growth probability of C. perfringens . The probability model was used to define the threshold of growth (probability > 0.1 or 0.2) of C. perfringens and validated using inoculated ground beef under optimum temperature. Inoculated ground beef was mixed with different combinations of STPP, NaL, and NaCl to observe growth or no growth of C. perfringens , and the probability was calculated from the formulation. If the threshold of growth was set to 0.2, the accuracy of the growth and no growth predictions was 95.7%, with 4.3% over-prediction of growth events (fail-safe). The results from this study suggested that proper combinations of STPP, NaL, and NaCl could be used to control the growth of C. perfringens in cooked beef under the optimum temperature. The results may also suggest that proper combinations of STPP, NaL, and NaCl in cooked meat and poultry products could be used to prevent the growth of C. perfringens during cooling. [ABSTRACT FROM AUTHOR]

Campylobacter is an important zoonotic pathogen found in livestock and can cause illness in humans following consumption of raw and undercooked meat products. The objectives of this study were to determine the prevalence of Campylobacter spp. in retail meat (poultry, turkey, pork and beef) purchased in Alberta, Canada and to assess antimicrobial resistance and genetic relatedness of recovered Campylobacter strains with previously isolated strains from clinical and environmental sources. A Comparative Genomic Fingerprinting (CGF) method was used for assessing genetic relatedness of isolates. A total of 606 samples comprising 204, 110, 145 and 147 samples of retail chicken, turkey, ground beef and pork, respectively, were obtained. Campylobacter was isolated from 23.5% (48/204) of chicken samples and 14.2% (8/110) of turkey samples. Pork and beef samples were negative for Campylobacter . Campylobacter jejuni was the most common (94.6%) spp. found followed by C. coli (5.4%). Resistance to tetracycline was found in 48.1% of isolates, followed by resistance to ciprofloxacin (5.5%), nalidixic acid (5.5%), azithromycin (1.78%), and erythromycin (1.78%). All isolates were susceptible to clindamycin, florfenicol, gentamicin and telithromycin. Tetracycline resistance was attributable to the presence of the tet O gene. CGF analysis showed that Campylobacter isolated from poultry meat in this study were genetically related to clinical isolates recovered from human infections and to those isolated from animals and the environment. [ABSTRACT FROM AUTHOR]

Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) is increasingly related to human infections. Farmers and veterinarians have the highest risk, but infections have also occurred in individuals without prior contact to livestock. Clonal complex (CC) 398 is the predominant LA-MRSA lineage causing human infections, and although pigs are the major source of CC398 worldwide, poultry and other animals are also reservoirs. This raises concern for transmission of MRSA via meat. In this study, the occurrence and characteristics of S. aureus isolated from Danish retail meat were examined with main focus on chicken meat. A total of 145 meat samples from Danish supermarkets were examined, including chicken (Danish, n = 102), turkey (non-Danish origin; n = 23), and pork (Danish, n = 20). S. aureus was detected in 69% of the meat samples. MRSA was detected in 19 meat samples (13%), resulting in MRSA prevalence of 4% of chicken, 52% of turkey, and 15% of pork. Three MRSA positive samples were obtained by direct plating ( Brilliance MRSA2), whereas 16 MRSA positive samples were detected only after enrichment (TSB + 6.5% NaCl and Brilliance MRSA2). Based on spa typing, 68% of MRSA isolates belonged to CC398 ( spa t034, t011, t2582, t108), and hereof one isolate derived from chicken (1%). Further findings were spa type t1430 (CC9) in turkey samples (16%) and the human-associated t008 (CC8) in chicken samples (16%). In conclusion, S. aureus was readily detected in Danish retail meat, but presence of MRSA in chicken meat is rare and it is unlikely to be an important transmission factor of MRSA to humans. [ABSTRACT FROM AUTHOR]

Influenced by production and storage processes and by seasonal changes the diversity of meat products microbiota can be very variable. Because microbiotas influence meat quality and safety, characterizing and understanding their dynamics during processing and storage is important for proposing innovative and efficient storage conditions. Challenge tests are usually performed using meat from the same batch, inoculated at high levels with one or few strains. Such experiments do not reflect the true microbial situation, and the global ecosystem is not taken into account. Our purpose was to constitute live stocks of chicken meat microbiotas to create standard and reproducible ecosystems. We searched for the best method to collect contaminating bacterial communities from chicken cuts to store as frozen aliquots. We tested several methods to extract DNA of these stored communities for subsequent PCR amplification. We determined the best moment to collect bacteria in sufficient amounts during the product shelf life. Results showed that the rinsing method associated to the use of Mobio DNA extraction kit was the most reliable method to collect bacteria and obtain DNA for subsequent PCR amplification. Then, 23 different chicken meat microbiotas were collected using this procedure. Microbiota aliquots were stored at − 80 °C without important loss of viability. Their characterization by cultural methods confirmed the large variability (richness and abundance) of bacterial communities present on chicken cuts. Four of these bacterial communities were used to estimate their ability to regrow on meat matrices. Challenge tests performed on sterile matrices showed that these microbiotas were successfully inoculated and could overgrow the natural microbiota of chicken meat. They can therefore be used for performing reproducible challenge tests mimicking a true meat ecosystem and enabling the possibility to test the influence of various processing or storage conditions on complex meat matrices. [ABSTRACT FROM AUTHOR]

Kitoza is a traditional meat product from Madagascar manufactured with strips of pork or beef. The process includes a first step of salting and mixing with spices followed by sun-drying or smoking step. As salting and drying select coagulase-negative staphylococci (CNS), our aim was to identify the CNS species in kitoza with the objective in the future of developing indigenous starters. Microbial analyses revealed that the only pathogenic bacterium enumerated was Staphylococcus aureus , which was found in 54% of the samples. The level of Enterobacteriaceae revealed a rather good hygienic quality of these products. CNS were confirmed in all the samples at high levels ranging from 5 to 7 log cfu/g. Identification of CNS species in a large collection of 829 isolates revealed 9 identified species, 7 for beef and 8 for pork kitoza. There were significant difference in the distribution of CNS species according to the type of meat and the process. Staphylococcus saprophyticus was the dominant species for sun-dried or smoked beef and sun-dried pork kitoza (73–75%), while for smoked pork kitoza Staphylococcus equorum (26%), S. saprophyticus (23%), Staphylococcus succinus (23%) and Staphylococcus epidermidis (17%) co-dominated. Some CNS could be used as indigenous starters in particular to compete against S. aureus . [ABSTRACT FROM AUTHOR]

Listeria monocytogenes isolates collected from final products and food contact surfaces of 10 ready-to-eat meat-based food products (RTEMP) producing industries were analyzed to relate their virulence-associated characteristics and genetic profiles with the hygiene assessment of those industries. Together with sample collection, an audit was performed to evaluate the implemented food safety management system and to investigate the specific audit requisites more associated to the occurrence of those L. monocytogenes serogroups frequently related with human disease. L. monocytogenes was present in 18% of the samples. The isolates ( n = 62) were serogrouped and detection of virulence-associated genes inlA , inlB , inlC and inlJ , and also plcA , hlyA , actA and iap was done by multiplex PCR. After this initial characterization, selected isolates ( n = 31) were submitted to antibiotic resistance testing by the disk diffusion method for the currently most used human and veterinary antibiotics and resistance was low. These isolates were also subtyped by pulsed-field gel electrophoresis. Genotyping and serogrouping of L. monocytogenes isolates revealed a genetically diverse population. Our data indicate that contamination of final products does not seem to be uniquely related to the sampled food surfaces. The occurrence of those L. monocytogenes serogroups more commonly associated with human disease in industries with a high hygienic audit classification could be the result of a previous identification of the pathogen, with an enforcement of the hygiene program without recognizing the real source of contamination. This reinforces the importance of a conjoined diagnosis using audit data and microbiological testing. Food safety management systems of those industries need improvement, particularly in cleaning and sanitizing operations, analytical control, preventive maintenance, personal hygiene and root cause analysis. [ABSTRACT FROM AUTHOR]

Salmonella spp., one of the most frequently reported bacteria, causes foodborne illness and economic losses. Due to the threat of increasing antibiotic resistant foodborne pathogens, application of bacteriophages as novel antibacterial agents in food matrices has become an emerging strategy. In this study, a novel Salmonella phage PS3-1 with high lytic activity against Salmonella Typhimurium was identified from previously isolated phages. PS3-1 belonged to the class Caudoviricetes with a broad host range, and had relatively short latent period (15 min), large burst size (92 PFU/cell), high pH stability (pH 3.0-11.0) and thermal tolerance (4-60 °C). Genome sequencing analysis showed that PS3-1 genome consisted of 107,110 bp DNA, without antibiotic resistance and virulence related genes. The results of growth curve and time-kill assay showed that PS3-1 not only inhibited the growth of S. Typhimurium, but also effectively decreased the viable cell counts (0.30-4.72 log) after 24-h incubation at 7, 25 and 37 °C (P < 0.05). Moreover, >1.28 log of established biofilm cells were effectively removed after 24-h treatment with PS3-1. Besides, PS3-1 significantly reduced the viability of S. Typhimurium in milk, lettuce, raw pork meat and ready-to-eat steamed-chicken breast at different temperatures (P < 0.05). These results demonstrated that PS3-1 may be an excellent antibacterial agent for controlling S. Typhimurium in food industry., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The main use of High Pressure Processing (HPP) in food processing is microorganism inactivation, and studies demonstrated that the characteristics of matrix and microorganisms can interfere on it. As the behavior of lactic acid bacteria exposed to different water activity (a w ) levels in a meat product is still unclear, this study aimed to determine the effect of pressure, time, and a w to inactivate Latilactobacillus sakei, a pressure resistant lactic acid bacteria (LAB) in a meat emulsion model through a response surface methodology. The meat emulsion model was designed with adjusted a w (from 0.940 to 0.960) and was inoculated with a pressure resistant LAB and processed varying pressure (400-600 MPa) and time (180-480 s), following the Central Composite Rotational Design (CCRD). The inactivation of the microorganism ranged from 0.99 to 4.12 UFC/g depending on the applied condition. At studied conditions, according to the best fitting and most significant polynomial equation (R 2 of 89.73 %), in a meat emulsion model, a w had no influenced on HPP inactivation on LAB (p > 0.05) and only pressure and holding time had significative impact on it. The results of experimental validation of the mathematical model were satisfactory, confirming the suitability of the model. The information obtained in the present study stands out the matrix, microorganism and process effects at HPP efficiency. The answers obtained support food processors in product development, process optimization and food waste reduction., Competing Interests: Declaration of competing interest The authors report no relationships that could be construed as a conflict of interest., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Red meat is a significant source of human nutrition, and the red meat industry contributes to the economy of nations. Nonetheless, there is a widespread global concern about public health issues posed by severe food safety incidents within the red meat industry. Most of these incidents are associated with foodborne disease outbreaks that impact individual consumers, food businesses and society. This study adopts a systematic search and review approach to identify three decades of published investigation reports of global foodborne disease outbreaks linked with the consumption of red meat and products made from them. The review aims to evaluate the critical features of these outbreak incidents to get insight into their contributing factors and root causes. In particular, this review discusses the transmission setting (origin of pathogenic agents), the food vehicles mostly incriminated, the causative pathogens (bacteria, viruses, and parasites) causing the most illnesses, and the most commonly reported contributing factors to the outbreaks. This information can help researchers and food business operators (FBOs) inform future risk assessment studies and support risk management activities in developing risk-mitigating strategies for the industry. Findings from this study suggest that implementing food safety management strategies which include adequate control measures at all stages of the food chain, from farm to fork, is imperative in preventing outbreak incidents. Of equal importance is the need for enhanced and sustained public education about the risk of foodborne illnesses associated with meat and its products whilst discouraging the consumption of raw meat products, especially by high-risk groups., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2023. Published by Elsevier B.V.)

Foods of animal origin are increasingly considered a source of extended spectrum β-lactamase (ESBL) producing bacteria which can disseminate throughout the food chain and become a health concern for humans. This work aimed to evaluate the occurrence of ESBL-producing Escherichia coli in 100 retail minced meat samples taken in markets in Pamplona, Colombia. A total of 19 ESBL-producing isolates were obtained, 18 identified as E. coli and one as E. fergusonii. Fifteen isolates (78.9 %) carried bla CTX-M and bla TEM genes, one (5.2 %) bla SHV and bla TEM genes, one isolate (5.2 %) carried bla CTX-M and one (5.2 %) bla SHV alone. The majority of CTX-M-positive E. coli isolates carried the bla CTX-M-15 gene (13 isolates), being the bla CTX-M-9 , bla CTX-M-2 , and bla CTX-M-8 (one isolate each) also detected. Two SHV-positive isolates presented the bla SHV-5 and bla SHV-12 allele. The isolate identified as E. fergusonii was positive for bla CTX-M-65 gene and mcr-1 gene. Sixteen isolates (84.2 %) belonged to phylogroups A and B1 and grouped together in the phylogenetic tree obtained by MLST; phylogroups E and F were also detected. Transfer of ESBL resistance was demonstrated for the E. fergusonii isolate. Whole genome sequencing of this isolate revealed the presence of plasmids carrying additional resistance genes. This investigation showed the high prevalence of ESBL-producing E. coli in retail samples of minced meat. Also, the isolation of a strain of E. fergusonii is an additional concern, as some resistance genes are located in mobile elements, which can be transmitted to other bacteria. These evidences support the increasing public health concern considering the spreading of resistance genes through the food chain., Competing Interests: Declaration of competing interest There are no conflicts of interest among authors., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

We determined the prevalence and types of extended-spectrum β-lactamase (ESBL)-producing and carbapenem-resistant Escherichia coli in raw retail beef, chicken, pork, fruit and vegetables in five UK regions in 2013–14. Raw meat (n = 397), and fruit and vegetable samples (n = 400) were purchased from retail stores in London, East Anglia, North West England, Scotland and Wales. Samples were tested for the presence of ESBL-producing E. coli by plating enriched samples on CHROMagar CTX and CHROMagar ESBL, for AmpC-type E. coli by plating on “CHROMagar FOX” (CHROMagar ECC + 16 mg/L cefoxitin), and for carbapenem-resistant E. coli by plating on CHROMagar KPC. Additionally, pre-enrichment counts were performed on the above agars, and on CHROMagar ECC. Isolates of interest were characterised by MALDI-ToF to confirm identification, by PCR for bla CIT, bla CTX-M, bla OXA , bla SHV and bla TEM genes; ESBL or bla CIT genes were sequenced. Only 1.9% and 2.5% of beef and pork samples, respectively were positive for ESBL-producing E. coli after enrichment compared with 65.4% of chicken samples. 85.6% positive samples from chicken meat carried bla CTX-M-1 ; bla CTX-M-15 was not detected. None of the fruits or vegetables yielded ESBL-producing E. coli and none of the meat, fruit or vegetable samples yielded carbapenem-resistant E. coli. Retail chicken was more frequently a source of ESBL-producing E. coli than were beef, pork, fruit or vegetables. None of the foodstuffs yielded E. coli with CTX-M-15 ESBL, which dominates in human clinical isolates in the UK, and none yielded carbapenem-resistant E. coli . [ABSTRACT FROM AUTHOR]

Campylobacter jejuni is a microaerophilic pathogen and leading cause of human gastroenteritis. The presence of C. jejuni encased in biofilms found in meat and poultry processing facilities may be the major strategy for its survival and dissemination in aerobic environment. In this study, Staphylococcus aureus , Salmonella enterica , or Pseudomonas aeruginosa was mixed with C. jejuni F38011 as a culture to form dual-species biofilms. After 4 days' exposure to aerobic stress, no viable C. jejuni cells could be detected from mono-species C. jejuni biofilm. In contrast, at least 4.7 log CFU/cm 2 of viable C. jejuni cells existed in some dual-species biofilms. To elucidate the mechanism of protection mode, chemical, physical and morphological features of biofilms were characterized. Dual-species biofilms contained a higher level of extracellular polymeric substances with a more diversified chemical composition, especially for polysaccharides and proteins, than mono-species C. jejuni biofilm. Structure of dual-species biofilms was more compact and their surface was > 8 times smoother than mono-species C. jejuni biofilm, as indicated by atomic force microscopy. Under desiccation stress, water content of dual-species biofilms decreased slowly and remained at higher levels for a longer time than mono-species C. jejuni biofilm. The surface of all biofilms was hydrophilic, but total surface energy of dual-species biofilms (ranging from 52.5 to 56.2 mJ/m 2 ) was lower than that of mono-species C. jejuni biofilm, leading to more resistance to wetting by polar liquids. This knowledge can aid in developing intervention strategies to decrease the survival and dispersal of C. jejuni into foods or environment. [ABSTRACT FROM AUTHOR]

The present study was conducted to preserve the microbial quality of chicken meat fillets during storage time by using sodium alginate active coating solutions incorporated with different natural antimicrobials including nisin, Cinnamomum zeylanicum (cinnamon), and rosemary essential oils (EOs) which were added individually and in combination. The samples were stored in refrigeration condition for 15 days and were analyzed for total viable count, Enterobacteriaceae count, lactic acid bacteria count, Pseudomonas spp. count, psychrotrophic count, and yeast and mold count, as well as fate of inoculated Listeria monocytogenes at 3-day intervals. Results indicated that values of tested microbial indicators in all samples increased during storage. Antimicrobial agents, when used in combination, had stronger effect in preserving the microbial quality of chicken meat samples rather than their individual use and the strongest effect was observed in samples coated with alginate solution containing both cinnamon and rosemary EOs (CEO + REO). However, all treatments significantly inhibited microbial growth when compared to the control ( P < 0.05). Therefore, based on the results of this study, application of alginate coating solutions containing nisin, cinnamon, and rosemary EOs as natural preservatives is recommended in meat products especially in chicken meats. [ABSTRACT FROM AUTHOR]

The aim of this study was to analyse the staphylococci isolated from ready-to-eat meat products, including pork ham, chicken cold cuts, pork sausage, salami and pork luncheon meat, sliced in the store to the consumer's specifications, along with species identification and determination of antibiotic resistance. Genes encoding staphylococcal enterotoxins, staphylococcal enterotoxin-like proteins, exfoliative toxins, and toxic shock syndrome toxin 1 were also investigated. From the 41 samples, 75 different staphylococcal isolates were obtained. Based on PCR-RFLP analysis of the gap gene using Alu I and Hpy CH4V restriction enzymes, the isolates were identified as Staphylococcus equorum (28%), S. vitulinus (16%), S. carnosus (14%), S. succinus (11%), S. xylosus (11%), S. saprophyticus (9%), S. warneri (9%), S. haemolyticus (1%) and S. pasteuri (1%). The incidence and number of resistances to antimicrobials was found to be species but not source of isolation dependent. All S. xylosus , S. saprophyticus , S. haemolyticus and S. pasteuri isolates showed antibiotic resistance. A lower percentage of resistance was recorded for S. warneri (71%) and S. vitulinus (58%), followed by S. equorum (57%), S. carnosus (50%) and S. succinus (50%). The most frequent resistance was observed to fusidic acid (43%). The mec A gene was amplified in 4% of the staphylococci. However, phenotypic resistance to methicillin was not confirmed in any of these isolates. On the other hand, the mec A gene was not detected in any of 9% of the isolates resistant to cefoxitin. It was also found that among 75 isolates, 60 (80%) harbored from 1 to 10 out of 21 analyzed superantigenic toxin genes. The most prevalent genes were: sei (36% isolates) among enterotoxins, seln (32% isolates) among enterotoxin-like proteins and eta encoding exfoliative toxin A (37% isolates). The findings of this study further extend previous observations that, when present in food, not only S. aureus but also other species of staphylococci could be of public health significance. [ABSTRACT FROM AUTHOR]

The objective of this study was to develop a predictive model for the inactivation of Salmonella spp. in ground beef jerky as a function of temperature (T), pH, potassium sorbate (PS), and final water activity (a w ). Following a central composite design, ground beef was combined with PS (0 to 0.3%, w/w), pH adjusted from 5 to 7, inoculated with a cocktail of 6 serotypes of Salmonella spp. and heat processed at temperatures between 65 and 85 °C until the final a w ranging from 0.65 to 0.85 was achieved. Surviving Salmonella cells were enumerated on tryptic soy agar overlaid with xylose lysine deoxycholate agar (pre-tempered to 47 °C) after incubation for 48 h at 30 °C. Bacterial inactivation was quantified in terms of logarithmic reductions of Salmonella counts (log 10 CFU/g) and inactivation rate (log 10 (CFU/g)/h). The results indicated that pH, PS and T significantly (p < 0.05) interacted to inactivate Salmonella in beef jerky. Decreasing meat pH significantly (p < 0.05) increased the efficacy of PS and T to reduce the levels of Salmonella spp. Beef jerky processed at 82 °C, pH 5.5, with 0.25% PS to a final a w of 0.7 resulted in a maximum Salmonella logarithmic reduction of 5.0 log 10 CFU/g and an inactivation rate of 1.3 log 10 (CFU/g)/h. The predictive model developed can be used to effectively design drying processes for beef jerky under low humidity conditions and thereby, ensuring an adequate degree of protection against risks associated with Salmonella spp. [ABSTRACT FROM AUTHOR]

Developing rapid and sensitive methods for the detection of pathogenic Escherichia coli O157:H7 remains a major challenge in food safety. The present study attempts to develop an immunofluorescence technique that uses Protein-A-coated, magnetic beads as the platform. The immunofluorescence technique described here is a direct detection method in which E. coli O157:H7 cells are labeled with tetramethylrhodamine (TRITC) fluorescent dye. TRITC-labeled bacteria are captured by the desired antibody (Ab), which is immobilized on the Protein-A magnetic beads. Fluorescence of the captured cells is recorded in a fluorescence spectrophotometer, where the fluorescence values are shown to be directly proportional to the number of bacteria captured on the immunobead. The formation of an immunocomplex is evidenced by the fluorescence of the beads under microscopy. The Ab immobilization procedure is also evidenced by microscopy using fluorescein isothiocyanate (FITC)-labeled Ab. The total experimental time, including preparation of the sample, is just 1 h. The minimum bacterial concentration detected by this method is 1.2 ± 0.06 × 10 3 CFU ml − 1 . The high specificity of this method was proved by using the specific monoclonal Ab (MAb) in the test. The proposed protocol was successfully validated with E. coli O157:H7-infected meat samples. This approach also opens the door for the detection of other bacterial pathogens using Protein-A magnetic beads as a detection platform. [ABSTRACT FROM AUTHOR]

Traditional sausages are often considered of superior quality to sausages inoculated with commercial starter cultures and this is partially due to the action of the typical house microflora. Penicillium nalgiovense is the species commonly used as starter culture for dry-cured meat production. Recently a new species, Penicillium salamii , was described as typical colonizer during salami seasoning. In order to understand its contribution to the seasoning process, two different experiments on curing of fresh pork sausages were conducted using P. salamii ITEM 15302 in comparison with P. nalgiovense ITEM 15292 at small and industrial scale, and the dry-cured sausages were subjected to sensory analyses. Additionally, proteolytic and lipolytic in vitro assays were performed on both strains. P. salamii ITEM 15302 proved to be a fast growing mould on dry-cured sausage casings, well adapted to the seasoning process, with high lipolytic and proteolytic enzymatic activity that confers typical sensory characteristics to meat products. Therefore, P. salamii ITEM 15302 was shown to be a good candidate as new starter for meat industry. [ABSTRACT FROM AUTHOR]

We have previously shown that potentially pathogenic isolates of Staphylococcus epidermidis occur at high incidence in ready-to-eat food. Now, within 164 samples of ready-to-eat meat products we identified 32 S. epidermidis isolates. In 8 isolates we detected the genes encoding for staphylococcal enterotoxins, but in 7 S. epidermidis isolates these genes were not stable over passages. One isolate designated 4S was shown to stably harbour sec and sel genes. In the genome sequence of S. epidermidis 4S we identified 21,426-bp region flanked by direct-repeats, encompassing sec and sel genes, corresponding to the previously described composite staphylococcal pathogenicity island (SePI) in S. epidermidis FRI909. Alignment of S. epidermidis 4S and S. epidermidis FRI909 SePIs revealed 6 nucleotide mismatches located in 5 of the total of 29 ORFs. Genomic location of S. epidermidis 4S SePI was the same as in FRI909. S. epidermidis 4S is a single locus variant of ST561, being genetically different from FRI909. SEC epi was secreted by S. epidermidis 4S to BHI broth ranging from 14 to almost 36 μg/mL, to milk ranging from 6 to 9 ng/mL, to beef meat juice from 2 to 3 μg/mL and to pork meat juice from 1 to 2 μg/mL after 24 and 48 h of cultivation, respectively. We provide the first evidence that S. epidermidis occurring in food bears an element encoding an orthologue to Staphylococcus aureus SEC, and that SEC epi can be produced in microbial broth, milk and meat juices. Regarding that only enterotoxins produced by S. aureus are officially tracked in food in EU, the ability to produce enterotoxin by S. epidermidis pose real risk for food safety. [ABSTRACT FROM AUTHOR]

Staphylococcus xylosus is frequently isolated from food of animal origin. Moreover, this species is one of the major starter cultures used for meat fermentation. Iron is a key element for growth and survival of bacteria. Meat is particularly rich in haemic (myoglobin and haemoglobin) and non-haemic (ferritin and transferrin) iron sources. Ferritin is a storage protein able to capture large quantities of iron. It is highly resistant to microbial attack and few microorganisms can use it as an iron source. Surprisingly, we found that the S. xylosus C2a strain grows in the presence of ferritin as a sole iron source. A three-cistron operon was highly overexpressed under ferritin iron growth conditions. We generated a deletion–insertion in the first gene of the operon and evaluated the phenotype of the mutant. The mutant showed decreased growth because it was less able to acquire iron from ferritin. Transcriptional analysis of the mutant revealed downregulation of several genes involved in the response to oxidative stress. This study characterized for the first time the capacity of a Staphylococcus to use iron from ferritin and revealed that a potential reductive pathway was involved in this acquisition. We hypothesize that this ability could give an advantage to S. xylosus in meat products. [ABSTRACT FROM AUTHOR]

The global spread of antimicrobial resistance (AMR) is alarming. Escherichia coli is a Gram-negative bacterium that causes healthcare-associated infections and is a major threat to public health. Currently, no comprehensive antimicrobial surveillance of multidrug-resistant E. coli of diverse phylogroups along the meat value chain has been implemented in Higashihiroshima, Japan. Therefore, by employing the One Health approach, 1183 bacterial isolates, including 303 recovered from meat samples in 2009, were screened for the presence of antimicrobial resistance determinants using multiplex PCR and DNA sequencing techniques. Seventy-seven non-duplicate E. coli isolates that harbored AMR genes were subjected to antimicrobial susceptibility testing and the detection of integrons. Phylogenetic characterization, which has not been previously investigated, was used to assign E. coli to one of the eight phylogroups. Twenty-six out of 33 (78.8%) and 34 out of 44 (77.3%) E. coli isolates from 2009 and 2021 exhibited multidrug resistance (MDR) phenotypes, respectively. The most common clinical resistance was observed against ampicillin, tetracycline, kanamycin, sulfamethoxazole/trimethoprim, cefotaxime, and chloramphenicol. Overall, 22.1% (17/77) of the E. coli isolates carried extended-spectrum β-lactamase (ESBL)-encoding genes and showed the ESBL-resistant phenotypes. For the two isolation years, AmpC/ESBL prevalence decreased from 42.4% in 2009 to 20.5% in 2021. The identified AMR genes included bla CTX-M-1 , bla CTX-M-2 , bla CTX-M-14 , bla CTX-M-15 , and bla SHV-12 (ESBL-types); bla SHV-1 , bla TEM-1 , bla TEM-135 , and bla TEM-176 (narrow-spectrum types); bla CMY-4 , bla ADC-32 , bla ADC-216 , bla ACT-48 , and bla ACT-51 (AmpC types); and integrons. All E. coli isolates were negative for carbapenemase-encoding genes, whereas one isolate from 2009 carried mcr-5.1 allele. Approximately 52% of E. coli isolates identified in 2009 were assigned to phylogroup A compared to the 20.5% in 2021. Notably, the highest proportions of E. coli phylogroups exhibiting MDR were groups A, B1, and F, suggesting that members of these groups are mostly associated with drug resistance. This study highlights the role of meat as a significant reservoir of MDR E. coli and potential source for transmission of AMR genes. Our findings emphasize the importance of continuous monitoring to track the changes in the spread of antimicrobial resistance in the food chain., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Tadashi Shimamoto reports financial support and administrative support were provided by Hiroshima University., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Shiga toxin producing Escherichia coli (STEC) continues to cause foodborne outbreaks associated with beef and beef products despite consistent use of antimicrobial interventions. In this study, the influence of antibiotic resistance (ABR) in E. coli O157:H7 H1730, O157:H7 43,895, O121:H19 and O26:H11 on tolerance to peroxyacetic acid (PAA) was evaluated. Further, bactericidal concentrations of PAA in the presence of nutrient rich media (Tryptic Soy Broth, TSB and beef exudates) and nutrient deficient media (Sterile Deionized Water, SDW and Phosphate Buffered Saline, PBS) were evaluated for all bacterial strains. Antibiotic resistance to ampicillin (amp C), or ampicillin and streptomycin (amp P strep C) was generated in each bacterial strain through incremental exposure to the antibiotics or by plasmid transformation (n = 12 total strains). The mean bactericidal concentrations of PAA were higher (p ≤ 0.05) in nutrient rich media (205.55 ± 31.11 in beef exudate and 195.83 ± 25.00 ppm in TSB) than in nutrient deficient media (57.91 ± 11.97 ppm in SDW and 56.66 ± 9.56 ppm in PBS). Strain O157: H7 ampP strepC was the most tolerant to PAA (p ≤ 0.05). At 200 ppm in nutrient rich media and 60 ppm in nutrient deficient media, all bacterial strains declined in population to below the limit of detection. Analysis of the beef exudates indicated the presence of diverse amino acids that have been associated with acid tolerance. The results from this study indicate that beef exudates could contribute to acid tolerance and suggest that some STEC bacterial strains with certain ABR profiles might be more tolerant to PAA., Competing Interests: Declaration of competing interest The authors have no affiliation with any organization with a direct or indirect financial interest in the subject matter discussed in the manuscript., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Recent epidemiological evidence suggests that pork products may be vehicles for the transmission of Shiga toxin-producing Escherichia coli (STEC) to humans. The severe morbidity associated with STEC infections highlights the need for research to understand the growth behavior of these bacteria in pork products. Classical predictive models can estimate pathogen growth in sterile meat. However, competition models considering background microbiota reflect a more realistic scenario for raw meat products. The objective of this study was to estimate the growth kinetics of clinically significant STEC (O157, non-O157, and O91), Salmonella, and generic E. coli in raw ground pork using competition primary growth models at temperature abuse (10 and 25 °C) and sublethal temperature (40 °C). A competition model incorporating the No lag Buchanan model was validated using the acceptable prediction zone (APZ) method where >92 % (1498/1620) of the residual errors fell within the APZ (pAPZ > 0.70). The background microbiota (mesophilic aerobic plate counts, APC) inhibited the growth of STEC and Salmonella indicating a simple one-directional competitive interaction between pathogens and the mesophilic microbiota of ground pork. The maximum specific growth rate (μ max ) of all the bacterial groups was not significantly different (p > 0.05) based on fat content (5 vs 25 %) except for generic E. coli at 10 °C. E. coli O157 and non-O157 behaved similarly in terms of μ max and maximum population density (MPD). Salmonella showed a similar (p > 0.05) μ max to E. coli O157 and non-O157 at 10 and 40 °C but a significantly higher rate (p < 0.05) at 25 °C. STEC were more prone to be inhibited by APC than Salmonella at 10 and 25 °C. The μ max of O91 was lower (p < 0.05) than other STEC and Salmonella at 10 and 25 °C but similar (p > 0.05) at 40 °C. Generic E. coli showed a two- to five-times higher (p < 0.05) μ max (0.028 ± 0.011 log 10  CFU/h) than other bacterial groups (0.006 ± 0.004 to 0.012 ± 0.003 log 10  CFU/h) at 10 °C making it a potential indicator bacteria for process control. Industry and regulators can use competitive models to develop appropriate risk assessment and mitigation strategies to improve the microbiological safety of raw pork products., Competing Interests: Declaration of competing interest All authors have participated in (a) conception and design, or analysis and interpretation of the data; (b) drafting the article or revising it critically for important intellectual content; and (c) approval of the final version. This manuscript has not been submitted to, nor is under review at, another journal or other publishing venue. The authors have no affiliation with any organization with a direct or indirect financial interest in the subject matter discussed in the manuscript., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Vacuum packaging is widely used for extending the shelf life of commercial fresh meat products. It also ensures product hygiene during distribution and storage. However, very little information exists concerning the effects of vacuum packaging on the shelf life of deer meat. One of our aims was to evaluate how storage under vacuum at 4 °C affects the microbial quality and safety of white-tailed deer (Odocoileus virginianus) meat cuts. This was assessed in a longitudinal study based on sensory analyses and measurements of (1) mesophilic aerobic bacteria (MAB), (2) lactic acid bacteria (LAB), (3) enterobacteria (EB), (4) and Escherichia coli (EC) counts, and the presence of foodborne pathogens (Campylobacter, Salmonella, stx-harbouring E. coli (STEC), Yersinia and Listeria). Microbiomes were additionally investigated by 16S rRNA gene amplicon sequencing at the time of spoilage. In total, 50 vacuum-packaged meat cuts from the carcasses of 10 wild white-tailed deer harvested in southern Finland in December 2018 were analysed. A significant (p < 0.001) drop in the odour and appearance scores and a significant increase in MAB (p < 0.001) and LAB (p = 0.001) counts of the vacuum-packaged meat cuts were observed after 3 weeks of storage at 4 °C. A very strong correlation (rs = 0.9444, p < 0.001) between the MAB and LAB counts were found during the 5-week sampling period. Clear spoilage changes, manifested as sour off-odours (odour scores ≤2) and pale colour, were detected in the meat cuts spoilt after 3-week storage. High (≥8 log 10 cfu/g) MAB and LAB counts were also detected. According to the 16S rRNA gene amplicon analyses, Lactobacillus was the dominant bacterial genus in these samples, demonstrating that LAB can cause rapid spoilage of vacuum-packaged deer meat cuts stored at 4 °C. The rest of the samples were spoilt after four or five weeks of storage, and a vast number of bacterial genera were identified in them. Listeria and STEC were detected by PCR in 50 % and 18 % of the meat cut samples, respectively, which may indicate a public health problem. Our results demonstrate that it is very challenging to ensure the quality and safety of vacuum-packaged deer meat stored at 4 °C, and freezing is therefore recommended to prolong the shelf life., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationship that could have influenced the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)