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Background For pathogen detection in food, there are occasions where samples cannot be processed immediately after selective enrichment or need to be reexamined days or weeks later for confirmation or retest. Objective This study aimed to investigate the effect of different prolonged period of storage of selective enrichments of food at 4 ± 2°C and room temperature (20–22°C) on the detection and isolation of Salmonella. Method This study included two experiments involving 34 types of foods to compare the effect of 4 ± 2°C and room temperature storage on the detection of Salmonella in 204 selective enrichments (Rappaport-Vassiliadis [RV] and Tetrathionate [TT] broths) during a 42-day storage (Experiment I); and to monitor the survival of Salmonella in 300 selective enrichments (RV and TT) with different pre-enrichment broths (Lactose broth [LB] or Buffered peptone water broth [BPW]), stored at 4°C for 60 days (Experiment II). All the samples were subjected to Salmonella analysis following the FDA BAM method. Results During multiple samplings, the positive detection rate for Salmonella remained consistent through Day 42 after selective enrichment, irrespective of Salmonella serotype, storage temperature, pre-enrichment broth, or selective enrichment broth in both Experiment I and II. However, on Day 60 sampling in Experiment II, seven previously positive results turned to negatives. These data indicated that storage of RV and TT enrichments at 4 ± 2°C or room temperature for up to 42 days after selective enrichment did not compromise the detection of Salmonella in the tested food categories, regardless of Salmonella serotypes and the broths used for pre-enrichment and selective enrichment. Conclusions At least for the food types studied in this experiment, the recovery of Salmonella from selective enrichments could be postponed for a limited period of time (e.g. <42 days) if needed without adversely affecting the test results. However, the delayed analysis of TT and RV enrichments does pose a risk of reduced detection sensitivity, as evidenced by the seven negative results on Day 60 compared to previous positives. We do not recommend or endorse delaying the analysis of TT and RV enrichments. Highlights In the food matrixes investigated in this experiment, the plating and isolation of Salmonella from selective TT and RV enrichments stored at 4 ± 2°C or room temperature could be deferred for a period (up to 42 days) without any negative effect on the test results, if necessary. [ABSTRACT FROM AUTHOR]

Salmonellosis is one of the most common foodborne diseases worldwide. Surface adherence and biofilm formation are among the main strategies evolved by Salmonella to survive under harsh conditions and are risk factors for its spread through the food chain. Owing to the increase in antimicrobial resistance, there is a growing need to develop other methods to control foodborne pathogens, and bacteriophages have been suggested as a potential alternative for this purpose. The aim of this study was to evaluate bacteriophages as a biological control of Salmonella enterica serotypes to inhibit and remove bacterial biofilms. A total of 12 S. enterica isolates were selected for this study, all of which were biofilm producers. Seven bacteriophages were tested, individually and in a cocktail, for their host range and efficiency of plating (EOP). The phage cocktail was evaluated for its antibiofilm effect against the Salmonella biofilms. Phages UPF_BP1, UPF_BP2, UPF_BP3, UPF_BP6, and 10:2 possessed a broad lytic spectrum and could infect all S. enterica strains. Phages 10:2, UPF_BP6, and UPF_BP3 had high EOP in 10, 9, and 9 out of the 12 S. enterica strains, respectively. The cocktail was able to infect all S. enterica strains and had a high EOP in 10 out of 12 S. enterica isolates, presenting a broader host range than any of the tested single phages. A wide variation of inhibition among strains was observed, ranging from 14.72% to 88.53%. Multidrug-resistant and strong biofilm producer strains showed high biofilm inhibition levels by phage cocktail. Our findings demonstrate the ability of the cocktail to prevent biofilm formation and remove formed biofilms of Salmonella. These results indicate that the phage cocktail is a promising candidate to be used as an alternative for the control of Salmonella biofilms through surface conditioning. [ABSTRACT FROM AUTHOR]

Successful detection of bacterial pathogens in food can be challenging due to the physical and compositional complexity of the matrix. Different mechanical/physical and chemical methods have been developed to separate microorganisms from food matrices to facilitate detection. The present study benchmarked a commercial tissue digestion system that applies both chemical and physical methods to separate microorganisms from tissues against stomaching, a standard process currently utilized by commercial and regulatory food safety laboratories. The impacts of the treatments on the physical properties of the food matrix were characterized along with the compatibility of the methods with downstream microbiological and molecular detection assays. The results indicate the tissue digestion system can significantly reduce the average particle size of the chicken sample relative to processing via a stomacher (P < 0.001) without adversely affecting either real-time PCR (qPCR) or plate counting assays, which are typically used to detect Salmonella. Furthermore, inoculated chicken treated with the GentleMACS resulted in a significant increase (P < 0.003) in the qPCR's detection capabilities relative to stomached controls. Cohen kappa (κ) coefficient and McNemar's test indicate the plating assays and PCR results agree with measurements obtained via the 3 M Molecular Detection System as defined in the MLG standard (κ > 0.62; P > 0.08). Collectively, the results demonstrate that the technique enables detection of pathogens in meat at lower levels of contamination using current industry standard technologies. [ABSTRACT FROM AUTHOR]

In this study, the antimicrobial resistance profiles of bacterial strains obtained from wild avian species recovered in wetlands of Northern Italy were described. Cloacal swabs collected from 67 aquatic birds, hunted or found dead in two private hunting grounds, were submitted to microbiological investigations and antimicrobial susceptibility testing using the Vitek 2 system, while specific PCR protocols were applied to screen for genes associated with the resistance. One hundred fifty-seven bacterial strains were characterized. The most frequent isolates were Enterococcus faecalis (36/157; 22.9%) and Escherichia coli (23/157; 14.6%). Seventy-seven isolates (77/157; 49%) were resulted resistant to at least one antibiotic, and eight isolates (8/157; 5%) were classified as multidrug resistant bacteria. Resistance for critically important antibiotics (linezolid, vancomycin, carbapenems, third-generation cephalosporins, and fluoroquinolones) was also described. Salmonella spp. was obtained from a Eurasian teal (Anas crecca), and it was subsequently analyzed by whole genome sequencing, revealing the serovar Salmonella Braenderup ST22. The phylogenetic analysis, performed with all ST22 described in 2021 and 2022, placed the strain under study in a large clade associated with human salmonellosis cases. These results suggest that migratory aquatic birds may be considered as relevant carriers of critically important antibiotic resistant bacteria and zoonotic food-borne pathogens potentially able to impact public health. [ABSTRACT FROM AUTHOR]

Modern requirements for 'green label' meat products have led to the design of novel antimicrobial innovations which prioritise quality, safety and longevity. Plasma-functionalised water (PFW), ultraviolet light and natural antimicrobial compositions have been investigated and optimised for control of foodborne pathogens like Campylobacter jejuni and Salmonella enterica serovar Typhimurium. However, given the adaptive mechanisms present in bacteria under external stresses, it is imperative to understand the effect that sublethal treatment may have on the bacterial transcriptome. In this study, Salmonella Typhimurium and C. jejuni were treated with sublethal doses of ultraviolet light, a citrus juice/essential oil marinade, and 'spark' or 'glow' cold plasma generation system-produced PFW. Immediately after treatment, cells were lysed and RNA was extracted and purified. mRNA was converted to cDNA by reverse transcription-PCR and sequenced by an Illumina MiSeq® system. Sequences were filtered and analysed using the Tuxedo workflow. Sublethal treatment of Campylobacter jejuni and Salmonella Typhimurium led to increased immediate cellular and metabolic activity, as well as diversification in protein and metabolic functioning. There was further expression of pathogenesis and virulence-associated traits associated with spark PFW and marinade treatment of Salmonella Typhimurium. However, similar concerns were not raised with glow PFW or UV-treated samples. This study provides science-based evidence of the efficacy of multi-hurdle antimicrobial system using green-label marinades and PFW or UV to inactivate pathogens without upregulating virulence traits in surviving cells. This study will inform policymakers and food industry stakeholders and reinforces the need to incorporate in-line novel technologies to ensure consumer safety. Key points: • Salmonella and C. jejuni showed increased cell activity in immediate response to stress. • Virulence genes showed increased expression when treated with natural antimicrobials and sPFW. • Reduced immediate transcriptomic response to gPFW and UV treatment indicates lower risk. [ABSTRACT FROM AUTHOR]

Recurring foodborne outbreaks, attributed to Escherichia coli O157:H7, Salmonella sp., and Listeria monocytogenes, have identified irrigation water as a potential source of contamination, and creating the necessity for safe irrigation water in produce cultivation, as emphasized by the Food Safety Modernization Act (FSMA). In response to this imperative, this study explored the efficacy of surfactant-modified zeolite (SMZ) enhanced with Cetrimonium bromide (CTAB) as a sustainable water purification solution for surface water. The SMZ was assessed to have the capacity to filter contaminated water with high loads of foodborne pathogens. A laboratory study was conducted using a 100 g SMZ column. A liter of phosphate-buffered saline (PBS) was inoculated for each pathogen at 6 log CFU mL-1 concentrations. The study found that SMZ modified with CTAB at a concentration exceeding 20% by weight, indicating the ratio of CTAB to the total mass of the modifying solution, could eliminate >6 log CFU mL-1 of Escherichia coli O157:H7 and Listeria monocytogenes and >2 log of Salmonella sp. Subsequent field testing in strawberry farms demonstrated the system's effectiveness, displaying significant bacterial reduction when contrasted with unfiltered pond water and sand filtration. The SMZ was able to filter more than 4 log CFU mL-1, from surface irrigation water spiked with a nonpathogenic Escherichia coli strain. The results indicate that the SMZ filtration approach holds promise as a remediation tool to control the risks of foodborne disease outbreaks associated with agricultural water. [ABSTRACT FROM AUTHOR]

Summary: Bacteria adherence to the surface and the resulting biofilm have serious harmful effects in food. Biofilm formation in foods can lead to food deterioration and disease transfer easily. Some alternative applications are being tried to remove biofilms. Among these, biosurfactants and bacteriophages are promising owing to their low toxicity, easy availability, and high activity. In our study, the action of phage and rhamnolipid, a biosurfactant, on the biofilm of Salmonella Infantis, which is an important pathogen in food, was examined. Additionally, the efficacy of phages in the biocontrol of foods was tested. It is observed that the phage significantly reduces the bacterial concentration in milk in the first 4 h at 4 °C and 25 °C and maintains its effect for 24 h at 4 °C. The p_S3 phage, rhamnolipid (RML), and p_S3 phage + RML mixture on the 48‐h biofilm decreased the biofilm mass by 44.9–81.8%, 20.8–81.1%, and 12–60%, respectively. On a 1‐week‐old biofilm, the p_S3 phage, RML, and p_S3 phage + RML mixture decreased the biofilm mass by 43–60%, 55–72%, and 49.7–61.7%, respectively. It is seen that the p_S3 phage and RML co‐administration on biofilm can be a biosafe application in food production facilities where it is a more effective application in removing the biofilm in long‐term exposure. [ABSTRACT FROM AUTHOR]

Salmonella enterica serovar Typhimurium (S. Typhimurium), an important foodborne pathogen, causes diarrheal illness and gastrointestinal diseases. S. Typhimurium survives and replicates in phagocytic and non-phagocytic cells for acute or chronic infections. In these cells, S. Typhimurium resides within Salmonella-containing vacuoles (SCVs), in which the phosphate (Pi) concentration is low. S. Typhimurium senses low Pi and expresses virulence factors to modify host cells. However, the mechanism by which host cells reduce the Pi concentration in SCVs is not clear. In this study, we show that through the TLR4-MyD88-NF-κB signaling pathway, S. Typhimurium upregulates PIT1, which in turn transports Pi from SCVs into the cytosol and results in Pi starvation in SCVs. Immunofluorescence and western blotting analysis reveal that after the internalization of S. Typhimurium, PIT1 is located on SCV membranes. Silencing or overexpressing PIT1 inhibits or promotes Pi starvation, Salmonella pathogenicity island-2 (SPI-2) gene expression, and replication in SCVs. The S. Typhimurium ΔmsbB mutant or silenced TLR4-MyD88-NF-κB pathway suppresses the expression of the SPI-2 genes and promotes the fusion of SCVs with lysosomes. Our results illustrate that S. Typhimurium exploits the host innate immune responses as signals to promote intracellular replication, and they provide new insights for the development of broad-spectrum therapeutics to combat bacterial infections. [ABSTRACT FROM AUTHOR]

Conflicting claims exist regarding pathogen growth in raw milk. A small pilot study was designed to provide definitive data on trends for pathogen growth and decline in raw bovine milk hygienically produced for direct human consumption. An independent laboratory conducted the study, monitoring growth and decline of pathogens inoculated into raw milk. Raw milk samples were inoculated with foodborne pathogens (Campylobacter, E. coli O157:H7, Listeria monocytogenes, or Salmonella) at lower (<162 colony forming units (CFU) per mL) and higher levels (<8,300 CFU/mL). Samples were stored at 4.4°C and quantified over time after inoculation (days 0, 3, 6, 9, 12, and 14) by standard culture-based methods. Statistical analysis of trends using the Mann-Kendall Trend Test and Analysis of Variance were conducted for 48 time series observations. Evidence of pathogen growth was documented for L. monocytogenes in 8 of 12 replicates (P = 0.001 to P = 0.028). Analysis of variance confirmed significant increases for L. monocytogenes at both initial levels in week 2. No evidence of growth was documented over 14 days for the three pathogens predominantly associated with raw milk outbreaks in the US (Campylobacter, E. coli O157:H7, and Salmonella). Further research is needed to characterize parameters for pathogen growth and decline to support re-assessment of risks that were based on incorrect assumptions about interactions of pathogens with the raw milk microbiota. [ABSTRACT FROM AUTHOR]

The objective of this study is to stochastically assess the inactivation probabilities of four common foodborne pathogens (Listeria, Salmonella, Escherichia coli, and Campylobacter) in chicken meat during ohmic heating (OH) in a salt solution. A mechanistic model was used to accomplish this, coupling heat transfer, laminar fluid flow, and the electric field, and solved numerically using COMSOL Multiphysics® v5.6. The 3D model represented 1000 particles randomly placed on the meat's surface to determine the 7-log reduction of bacterial load probability. These particles are virtual representatives of bacterial colonies in the model. The influence of uncertain input parameters (specific heat capacity and electrical conductivity) and OH conditions (salt concentration of the heating medium, applied voltage, and heating time) was explained using logistic regression. The same analysis was repeated for the slowest heating point of chicken meat, as well. According to the findings, cold spots are observed at the corners of the meat piece during OH, requiring additional attention to the meat surface temperature to prevent under-processing. Sensitivity analysis revealed that the applied voltage and brine concentration are the main factors affecting the inactivation probabilities of pathogenic bacterial cells on the chicken meat surface. Salmonella and Listeria may require higher electrical conductivity of chicken meat and longer processing times. The developed model enables predicting inactivation probabilities of microorganisms that can be found on the outer surface by measuring the core temperature of the meat. However, especially for bacteria with higher heat resistance, it is better to consider the cold spot temperature found in the corners of the food material during OH. [ABSTRACT FROM AUTHOR]

Salmonella spp. is a significant foodborne pathogen present in raw meat products and in the processing environment. It can be eliminated by thermal processes such as cooking. Time and temperature in the thermal process play an important role in eliminating this pathogen. The objective of this study is to determine the D- and z-values of Salmonella spp. in whole-muscle beef using the isothermal inactivation method in four temperatures at designated time intervals. Whole-muscle beef was inoculated with 7 to 8 log10 CFU/mL of Salmonella Typhimurium and Salmonella Enteritidis. The inoculated meat samples were heat treated at 58 °C, 60 °C, 62 °C, and 64 °C. At each temperature, Salmonella spp. survival rate was plotted and the D- and z-values were obtained by linear regression of the survival curve. The D-values for the thermal inactivation of whole-muscle beef are D58 °C=5.41 min, D60 °C=2.03 min, D62 °C=0.46 min, and D64 °C=0.18 min, while the z-value obtained was 3.94 °C. These findings will assist food processors in designing the critical limits on the critical control points of the cooking process that ensure safety against Salmonella spp. in cooked whole-muscle beef. [ABSTRACT FROM AUTHOR]

In this study, we developed a sensitive immunochromatographic analysis (ICA) of the Salmonella typhimurium bacterial pathogen contaminating food products and causing foodborne illness. The ICA of S. typhimurium was performed using Au@Pt nanozyme as a label ensuring both colorimetric detection and catalytic amplification of the analytical signal due to nanozyme peroxidase-mimic properties. The enhanced ICA enabled the detection of S. typhimurium cells with the visual limit of detection (LOD) of 2 × 102 CFU/mL, which outperformed the LOD in the ICA with traditional gold nanoparticles by two orders of magnitude. The assay duration was 15 min. The specificity of the developed assay was tested using cells from various Salmonella species as well as other foodborne pathogens; it was shown that the test system detected only S. typhimurium. The applicability of ICA for the determination of Salmonella in food was confirmed in several samples of milk with different fat content, as well as chicken meat. For these real samples, simple pretreatment procedures were proposed. Recoveries of Salmonella in foodstuffs were from 74.8 to 94.5%. Due to rapidity and sensitivity, the proposed test system is a promising tool for the point-of-care control of the Salmonella contamination of different food products on the whole farm-to-table chain. [ABSTRACT FROM AUTHOR]

Salmonella enterica is one of the most commonly reported foodborne pathogens by public health agencies worldwide. In this study, the multilocus sequence typing (MLST) population structure and frequency of antimicrobial resistance (AMR) genes were evaluated in S. enterica strains from Mexico (n = 2561). The most common sources of isolation were food (44.28%), environment (27.41%), animal-related (24.83%), and human (3.48%). The most prevalent serovars were Newport (8.51%), Oranienburg (7.03%), Anatum (5.78%), Typhimurium (5.12%), and Infantis (4.57%). As determined by the 7-gene MLST scheme, the most frequent sequence types were ST23, ST64, and ST32. The core genome MLST scheme identified 132 HC2000 and 195 HC900 hierarchical clusters, with the HC2000_2 cluster being the most prevalent in Mexico (n = 256). A total of 78 different AMR genes belonging to 13 antimicrobial classes were detected in 638 genomic assemblies of S. enterica. The most frequent class was aminoglycosides (31.76%), followed by tetracyclines (12.53%) and sulfonamides (11.91%). These results can help public health agencies in Mexico prioritize their efforts and resources to increase the genomic sequencing of circulating Salmonella strains. Additionally, they provide valuable information for local and global public health efforts to reduce the impact of foodborne diseases and AMR. [ABSTRACT FROM AUTHOR]

Due to the extensive use of antibiotics, the increase of infections caused by antibiotic-resistant bacteria is now a global health concern. Phages have proven useful for treating bacterial infections and represent a promising alternative or complement to antibiotic treatment. Yet, other alternatives exist, such as bacteria-produced non-replicative protein complexes that can kill their targeted bacteria by puncturing their membrane (Tailocins). To expand the repertoire of Tailocins available, we suggest a new approach that transforms phages into Tailocins. Here, we genetically engineered the virulent Ackermannviridae phage S117, as well as temperate phages Fels-1, -2 and Gifsy-1 and -2, targeting the food pathogen Salmonella, by deleting the portal vertex or major capsid gene using CRISPR-Cas9. We report the production of Tailocin particles from engineered virulent and temperate phages able to kill their native host. Our work represents a steppingstone that taps into the huge diversity of phages and transforms them into versatile puncturing new antimicrobials. [ABSTRACT FROM AUTHOR]

Background: Salmonella spp. and pathogenic strains of Escherichia coli are among the major foodborne zoonotic pathogens. These bacterial pathogens cause human illnesses characterized by hemorrhagic colitis, vomiting, nausea, and other agent-related symptoms. The increasing occurrence of antimicrobial resistance in these pathogens is also a serious public health concern globally. Regular surveillance of phenotypes and genotypes of Salmonella spp. and Escherichia coli from animal-derived foods is necessary for effective reduction and control of these foodborne pathogens. This study was conducted to assess the occurrence, antimicrobial resistance, virulence genes and genetic diversity of Salmonella spp. and E. coli isolates from fresh Nile tilapia obtained from retail markets in Nairobi, Kenya. Methods: A total of 68 fresh Nile tilapia fish samples were collected from retail markets and used for isolation of Salmonella spp. and E. coli. Antimicrobial susceptibilities of the isolates weretested by Kirby-Bauer agar disc diffusion method. According to the antimicrobial resistance profiles, the multi-drug resistant isolates were identified by 16 S rRNA sequencing and phylogenetic analysis using the Bayesian inference method. The MDR Salmonella spp. and E. coli isolates were subjected to PCR-based screening for the detection virulence and antibiotic resistance genes. Results: The prevalence of contamination of the fish samples with Salmonella spp. and E.coli was 26.47% and 35.29% respectively. Overall phenotypic resistance among the Salmonella spp. ranged from 5.5% for ceftazidime, chloramphenicol, meropenem, nitrofurantoin and streptomycin and 22.2% for penicillin-G. For E. coli phenotypic resistance ranged from 4.2% for ceftazidime and chloramphenicol and 25% for rifampicin. Multi-drug resistance was observed in three Salmonella spp. and two E. coli isolates. Results of 16 S rRNA sequences, sequence alignment and phylogenic trees confirmed the identified MDR isolates as S. typhymurium WES-09, S. typhymurium MAK-22, S. typhimurium EMB-32 and E. coli MAK-26 and E. coli LAN-35. The presence of antibiotic-resistance genes belonging to β-lactamases, tetracycline, sulfonamide, trimethoprim and aminoglycosides-resistant genes were detected in all the identified MDR isolates. Conclusions: The findings from this study indicate that Nile tilapia (Oreochromis niloticus) sold in retail markets can acts as reservoirs of Salmonella spp. and E. coli pathogens linked to human disease, some of which were multidrug resistance to critically important antimicrobials. Both microorganisms are of zoonotic significance and represent a significant public health risk to the society. [ABSTRACT FROM AUTHOR]

Salmonella enterica and Campylobacter jejuni are some of the common foodborne pathogens causing gastrointestinal illnesses worldwide. The development of sensitive and specific detection methods is essential to ensure food safety. Dye-based real-time PCR assay using SYBR™ GreenER™ dye was developed for the detection of Salmonella enterica and Campylobacter jejuni. Designed primer sets specifically targeting the genes ompF and omp50 in Salmonella and Campylobacter, respectively, were utilised in the study. The assay was able to detect Salmonella and Campylobacter at as low as 50 fg/μl and 10 fg/μl, respectively. Specificity analysis performed using 16 different bacterial strains to check for cross- reactivity with the respective bacteria found the assay to be specific to Salmonella and Campylobacter. The assay successfully detected Salmonella enterica in inoculated food at as low as 5 fg/reaction for some food samples. Meanwhile, the detection limit for Campylobacter jejuni in all inoculated food samples was 2000 fg/reaction. The coefficient variations (CV%) of the assays for both pathogens indicated that the assays were highly reproducible. Therefore, the developed real-time PCR assays for both Salmonella enterica and Campylobacter jejuni detections were specific and sensitive and can be used for rapid screening to detect these foodborne pathogens. [ABSTRACT FROM AUTHOR]

Salmonella is an important foodborne pathogen, which can cause serious public health problems. Rapid and accurate detection of Salmonella infection and drug resistance mutations in patients will provide timely guidance for clinical treatment and avoid disease progression and other related clinical problems. Here, we established a highly sensitive and quick method for Salmonella and drug resistance mutation detection based on polymerase chain reaction (PCR) and CRISPR-lbCas12a system and evaluated its practicability with clinical samples. Specific CRISPR RNAs (crRNAs) and primers are designed for Salmonella DNA and parC gene S80I mutation diagnosis. CrRNAs with and without phosphorylated modification and different crRNA preparation methods are used to assess the effect on the detection system. After optimization, we detected as low as one copy of Salmonella DNA and drug resistance mutation parC S80I with the Salmonella DNA standard. For 94 clinical samples, this method also showed high sensitivity (100%, 95% CI: 84.98–100%) and specificity (98.48%, 95% CI: 90.73–99.92%) with less time (3 h) than plate culture (16 h) and conventional antimicrobial susceptibility testing (over 16 h). Besides, one parC S80I mutant strain was detected, which is consistent with the result of DNA sequencing. Taken together, we established a highly sensitive and specific method for Salmonella infection and parC S80I drug resistance mutation detection with fewer reagents and ordinary instruments. This assay has wide application prospects for fast detection of pathogen (bacterium and virus) infection, drug resistance determination, and proper treatment guidance. [ABSTRACT FROM AUTHOR]

Traditional immunoassays exhibit insufficient screening sensitivity for foodborne pathogens due to their low colorimetric signal intensities. Herein, we propose an ultrasensitive dynamic light scattering (DLS) immunosensor for Salmonella based on a "cargo release-seed growth" strategy enabled by a probe, namely gold nanoparticle-decorated covalent organic frameworks (COF@AuNP). Large amounts of AuNPs in COF@AuNP can be released by acid treatment-induced decomposition of the imine-linked COF, and then they are enlarged via gold growth to generate a dramatically enhanced light-scattering signal, leading to a vast improvement in detection sensitivity. Based on an immunomagnetic microbead carrier, the proposed DLS immunosensor is capable of detecting trace Salmonella in milk in the range of 2.0 × 102–2.0 × 105 CFU mL−1, with a limit of detection of 60 CFU mL−1. The immunosensor also demonstrated excellent selectivity, good accuracy and precision, and high reliability for detecting Salmonella in milk. [ABSTRACT FROM AUTHOR]

Salmonella serotypes are considered as one of the most important foodborne pathogens. Eggs are a main source of the contamination caused by these pathogens and diseases in humans and the prevalence of the salmonellosis. This study was aimed to isolate Salmonella enteritidis from industrial eggs collected from different areas of Qazvin city, Iran in the year 2020.In this cross-sectional study, 200 eggs were collected randomly (including 100 industrial packaged eggs and 100 industrial tray eggs) from the retail and stores located in Qazvin city, Iran. After culturing of eggshells and egg contents according to the classic methods, suspected colonies were confirmed by PCR assay. Salmonella was detected in 10% (4/40) among the egg samples. Salmonella was isolated from 0% (0/40) and 10% (4/40) of eggshells and egg contents, respectively. Isolates from positive egg samples were characterized as S. Typhimurium. Salmonella Typhimurium is the most prevalent serotype of egg contamination in Qazvin city, Iran. It can be regarded as the risk evaluation of possible human foodborne diseases associated with the consumption of contaminated eggs. [ABSTRACT FROM AUTHOR]

Salmonella is a widespread foodborne pathogen that can exhibit multidrug resistance (MDR; resistance to ≥3 antimicrobial classes). Therefore, the development of new preventative measures against MDR Salmonella is highly important. Bacterial antibiotic resistance is commonly mediated by efflux pumps. In this study, two compounds that block efflux pump activity, 1-(1-Naphthylmethyl)-Piperazine (NMP) and Phenylalanine-arginine β-naphthylamide (PaβN), were tested with the antibiotic tetracycline to determine if a synergistic reduction in resistance could be achieved in tetracycline-resistant Salmonella. The efflux pump inhibitors (EPIs) reduced Salmonella resistance to tetracycline by 16 to 32-fold in several tetracycline resistant isolates. For example, the tetracycline minimum inhibitory concentration (MIC) for MDR Salmonella enterica serovar I 4,[5],12:i:- USDA15WA-1 (SX 238) was 256 μg/mL. However, in the presence of NMP (250 μg/mL), the MIC dropped to 8 μg/mL which is below the Clinical Laboratory Standards Institute (CLSI) breakpoint for tetracycline resistance in Salmonella (≥16 μg/mL). Confocal and transmission electron microscopy revealed NMP-mediated damage to Salmonella membranes at a higher concentration (1000 μg/mL), implying that the EPI disrupts membrane morphology which can lead to cell death; however, this effect was dependent on NMP concentration, as NMP blocked efflux activity with less of a membrane-disrupting effect at a lower concentration (250 μg/mL). These findings suggest that the use of EPIs can reduce the MIC of tetracycline and restore the effectiveness of the antibiotic against tetracycline-resistant Salmonella. • NMP synergistically reduced tetracycline resistance in Salmonella. • Efflux pump inhibition restored tetracycline efficacy against resistant Salmonella. • NMP caused membrane destabilization in Salmonella at higher concentrations. [ABSTRACT FROM AUTHOR]

Escherichia coli O157:H7, Staphylococcus aureus, and Salmonella are major foodborne pathogens that are widespread in nature and responsible for several outbreaks of food safety accidents. Thus, a rapid and practical technique (PMA-mPCR) was developed for the simultaneous detection of viable E. coli O157:H7, S. aureus, and Salmonella in pure culture and in a food matrix. To eliminate false positive results, propidium monoazide (PMA) was applied to selectively suppress the DNA amplification of dead cells. The results showed the optimum concentration of PMA is 5.0 µg/mL. The detection limit of this assay by mPCR was 103 CFU/mL in the culture broth, and by PMA-mPCR was 104 CFU/mL both in pure culture and a food matrix (milk and ground beef). In addition, the detection of mixed viable and dead cells was also explored in this study. The detection sensitivity ratio of viable and dead counts was less than 1:10. Therefore, the PMA-mPCR assay proposed here might provide an efficient detection tool for the simultaneous detection of viable E. coli O157:H7, S. aureus, and Salmonella and also have great potential for the detection and concentration assessment of VBNC cells. [ABSTRACT FROM AUTHOR]

Monitoring of food products by government agencies for their compliance to regulatory limits is an essential step in controlling foodborne outbreaks. For monitoring purposes, an extensive setup of the surveillance system is used, which involves ISO 17025:2017 accredited laboratories for food testing. Participation in proficiency testing (PT) programs is a requirement of ISO 17025:2017, which ensures data accuracy and analyst competency. Participation in PT schemes is costly for laboratories in developing countries as most of the commercial suppliers are situated in the United States and Europe. The literature or data available on creation of microbiological proficiency testing is scanty as much of the data available with commercial suppliers are trade secrets, and there is only 0.06% of research articles available in the Scopus database on the topic. In this review article, an attempt is made to understand the factors impacting the survival of two important foodborne pathogens, i.e., Escherichia coli and Salmonella spp., by extracting information available from growth studies and root-cause analysis of various food safety incidents and recalls. Utilization of this information in the development of PT samples is discussed in this review article along with a focus on the availability of PT samples and associated ISO standards to formulate homogeneous and stable PT samples. This review article elaborates on the focus areas that can be considered by PT providers (PTP)—for example, initial inoculum level and preparation, strain type, microbial growth phase, the impact of different types of food matrixes including low-moisture food, antimicrobial components, pH, presence of competitor microbes, and environmental conditions involving storage temperature, time, and relative humidity. These focus areas can be used to successfully create PT samples by PTP in developing countries. [ABSTRACT FROM AUTHOR]

Free fatty acids (FFAs) have long been acknowledged for their antimicrobial activity. More recently, long-chain FFAs (>12 carbon atoms) are receiving increased attention for their potent antivirulence activity against pathogenic bacteria. In the gastrointestinal tract, foodborne pathogens encounter a variety of long-chain FFAs derived from the diet, metabolic activities of the gut microbiota, or the host. This review highlights the role of long-chain FFAs as signaling molecules acting to inhibit the infectious potential of important foodborne pathogens, including Salmonella and Listeria monocytogenes. Various long-chain FFAs interact with sensory proteins and transcriptional regulators controlling the expression of infection-relevant genes. Consequently, long-chain FFAs may act to disarm bacterial pathogens of their virulence factors. Understanding how foodborne pathogens sense and respond to long-chain FFAs may enable the design of new anti-infective approaches. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the behavior of Salmonella enterica and Listeria monocytogenes in processed date paste and syrup at different temperatures. Commercial products were inoculated with approximately 6 log CFU/mL of S. enterica or L. monocytogenes and stored at 4, 10, and 24°C for 90 days. S. enterica was able to survive in date products until the end of storage at 4°C. At this temperature, numbers decreased by 2.1 log CFU/g in date paste and by 3.4 log CFU/g in date syrup; however, at 10°C, cells were reduced >4.2 log CFU/g and were undetectable by direct plating in date paste or by enrichment (complete elimination) in syrup. Further, at 24°C, complete elimination of S. enterica was achieved in date paste and syrup by 30 and 7 days, respectively. L. monocytogenes numbers decreased by 1.4, 4.4, and >4.6 log CFU/g in date paste stored at 4, 10, and 24°C for 90 days, respectively. In date syrup, numbers of L. monocytogenes decreased to undetectable levels by 50, 14, and 4 days at 4, 10, and 24°C, respectively, by direct plating and complete elimination was observed at 10 and 24°C by 50 and 30 days of storage, respectively. The initial pH values of date paste and syrup were 4.7 and 4.8, respectively, and remained stable until the end of storage except for L. monocytogenes‐inoculated syrup. Practical Application: Salmonella enterica and Listeria monocytogenes can easily survive in date paste and syrup particularly at refrigerator temperature, which explains the necessity of preventing the contamination of date products with foodborne pathogens. [ABSTRACT FROM AUTHOR]

Salmonella enteritidis is one of the most common foodborne pathogens. Many methods have been developed to detect Salmonella, but most of them are expensive, time-consuming, and complex in experimental procedures. Developing a rapid, specific, cost-effective, and sensitive detection method is still demanded. In this work, a practical detection method is presented using salicylaldazine caprylate as the fluorescent probe, which could be hydrolyzed by caprylate esterase liberated from Salmonella lysed by phage, to form strong fluorescent salicylaldazine. The Salmonella could be detected accurately with a low limit of detection of 6 CFU/mL and a broad concentration range of 10–106 CFU/mL. Moreover, this method was successfully used for the rapid detection of Salmonella in milk within 2 h through pre-enrichment by ampicillin-conjugated magnetic beads. The novel combination of fluorescent turn-on probe salicylaldazine caprylate and phage ensures this method has excellent sensitivity and selectivity. [ABSTRACT FROM AUTHOR]

Salmonella is a common foodborne pathogen worldwide. The use of bacteriophage-encoded endolysins as antimicrobial agents is a promising approach for controlling pathogenic contamination. In this context, a recombinant endolysin named rLysJNwz, consisting of a single domain falling with the L-alanogyl-D-glutamate peptidase-like family, was cloned, expressed, and characterized. The yield of rLysJNwz was about 25 mg/L. Synergy between 7.5 μg/mL rLysJNwz and 0.5 mmol/L EDTA could decrease the viable counts of Salmonella NCTC 8271 by 93.28%. A synergistic effect between rLysJNwz and polymyxin B was demonstrated, exhibiting the MIC of polymyxin B decreased by twofold. Specifically, rlysJNwz had strong thermostability at temperatures (4–95 °C) and maintained high activity at pHs from 5.0 to 11.0. rlysJNwz was a metal ion‐dependent peptidase, which activated by divalent metal ions such as Zn2+, Mn2+, or Ca2+. Moreover, it was also found that the synergism of rlysJNwz and EDTA had bactericidal activities against a broad range of Gram-negative bacteria, including several multidrug-resistant bacteria. The application of rLysJNwz combined with EDTA was evaluated on contaminated eggs and lettuce for 60 min, displaying more than 86.7% and 86.5% reduction of viable Salmonella, respectively. Hence, these results suggest that rLysJNwz is a potential antibacterial agent to control Salmonella, especially antibiotic-resistant pathogen contamination in the field of food safety. Key points: • rLysJNwz shows lytic activities against a broad range of Gram-negative bacteria. • Endolysin rLysJNwz is a stable metalloenzyme and has high thermostability. • rLysJNwz and 0.5 mmol/L EDTA synergistically inactivate Salmonella on eggs and lettuce. [ABSTRACT FROM AUTHOR]

Objective. The aim of this study is to evaluate the hygienic and sanitary quality of bovine milk from dairy farms of Nariño, Colombia by determining the presence of environmental microorganisms of public health importance such as Salmonella spp., Escherichia coli O157, Listeria monocytogenes, Staphylococcus aureus and Yersinia enterocolitica and to evaluate the impact that the rainy seasons have on milk quality Materials and methods. Milk samples were taken in 180 farms located in four natural subregions, both in the high rainfall season and in the low rainfall season. Mesophilic aerobic count, a somatic cell count by automated methods, and a total coliform count in 3M Petrifilm® plates were done to each milk sample. Detection of Salmonella spp., Escherichia coli O157:H7 and Listeria monocytogenes was done by the 3M MDS system, Staphylococcus aureus and Yersinia enterocolitica were isolated by conventional microbiology techniques. Results. The highest somatic cell counts were found during the high rain season. The median of the mesophilic, total coliform and somatic cell counts were 20,085 CFU/ml, 265 CFU/ml and 219,170 cells/ml, respectively, with no significant differences in the two rainy periods. Neither Salmonella spp. nor E. coli O157/H7 were detected. There was no significant difference among the presence of Listeria sp., L. monocytogenes, Y. enterocolitica, Staphylococcus aureus and coagulase negative Staphylococcus between the two rainy seasons. Conclusions. 80% of the milk samples met the hygienic and sanitary quality standards and no influence of the sampling period on the hygienic quality of the milk was observed. [ABSTRACT FROM AUTHOR]

Foodborne pathogens can have devastating repercussions and significantly threaten public health. Therefore, it is indeed essential to guarantee the sustainability of our food production. Food preservation and storage using nanocomposites is a promising strategy. Accordingly, the present research's objectives were to identify and isolate a few foodborne pathogens from food products, (ii) synthesize and characterize silver nanoparticles (AgNPs) using wet chemical reduction into the lamellar space layer of montmorillonite (MMT), and (iii) investigate the antibacterial potential of the AgNPs/MMT nanocomposite versus isolated strains of bacteria. Six bacterial species, including Escherichia coli, Salmonella spp., Pseudomonas aeruginosa, Staphylococcus aureus, Listeria monocytogenes, and Bacillus cereus were isolated from some food products (meat, fish, cheese, and vegetables). The Ag/MMT nanocomposite was synthesized and characterized using UV–visible spectroscopy, transmission electron microscopy, particle size analyzer, zeta potential, X-ray diffraction (XRD), and scanning electron microscopy with dispersive energy X-ray (EDX). The antibacterial effectiveness of the AgNPs/MMT nanocomposite further investigated distinct bacterial species using a zone of inhibition assay and microtiter-based methods. Nanoparticles with a narrow dimension range of 12 to 30 nm were identified using TEM analysis. The SEM was employed to view the sizeable flakes of the AgNPs/MMT. At 416 nm, the most excellent UV absorption was measured. Four silver metallic diffraction peaks were found in the XRD pattern during the study, and the EDX spectrum revealed a strong signal attributed to Ag nanocrystals. AgNPs/MMT figured out the powerful antibacterial action. The AgNPs/MMT nanocomposite confirmed outstanding minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against six isolates of foodborne pathogens, ranging from 15 to 75 µg/mL, respectively. The AgNPs/MMT's antibacterial potential against gram-negative bacteria was noticeably better than gram-positive bacteria. Therefore, the AgNPs/MMT nanocomposite has the potential to be used as a reliable deactivator in food processing and preservation to protect against foodborne pathogenic bacteria. This suggests that the nanocomposite may be effective at inhibiting the growth and proliferation of harmful bacteria in food, which could help to reduce the risk of foodborne illness. [ABSTRACT FROM AUTHOR]

Salmonella remains one of the most common foodborne pathogens worldwide, and its resistance to antimicrobials has increased considerably over the years. In this context, was evaluated the action of three bacteriophages isolated or combined in inhibiting the adhesion and removal of Salmonella Heidelberg biofilm on a polystyrene surface. The bacteriophages UPF_BP1, UPF_BP2, UPF_BP3 and a pool of them were used for biocontrol of Salmonella Heidelberg biofilms on polystyrene surface in the action times of 3, 6 and 9 h. Individual and combined phages exhibited reductions in Salmonella Heidelberg adhesion of up to 83.4% and up to 64.0% in removal of preformed biofilm. The use of synergistic combinations between the phages is the most indicated option due to its potential to reduce biofilms. The use of the bacteriophage pool in surface conditioning is an alternative in the control of Salmonella Heidelberg biofilms. [ABSTRACT FROM AUTHOR]

Simple Summary: In an era of increasingly complex global trade, continual evolution of production practices, and emerging threats from antibiotic resistance, new strategies for maintaining the health and performance of poultry flocks remain critical along with reducing risk from foodborne pathogens such as Salmonella Enteritidis (SE). Natural feed-additive technologies, often referred to as antibiotic alternatives, may play a key role. In this study, layer pullets were fed a control diet with or without a postbiotic feed additive and subsequently challenged directly or indirectly with SE at 16 weeks of age to evaluate the effect of the postbiotic for preventing or reducing SE colonization loads in birds directly or indirectly exposed to the pathogen. Within birds indirectly exposed to the SE inoculation, the postbiotic was associated with a significant reduction of SE-positive individual birds and their associated SE loads when compared to the control birds 7 days after inoculation, with non-significant yet explorable outcomes after 14 days post-challenge. These data support previous research findings in the literature indicating the postbiotic feed additive may aid in reducing SE in poultry production and may therefore be a candidate component of a comprehensive pre-harvest food-safety management plan. Determining the efficacy of feed-additive technologies utilized as pre-harvest food-safety interventions against Salmonella enterica may be influenced by factors including, but not limited to, mechanism of action, experimental design variables, Salmonella serovar(s), exposure dose, route, or duration in both controlled research and real-world field observations. The purpose of this study was to evaluate the dietary inclusion of a Saccharomyces cerevisiae fermentation-derived postbiotic (SCFP) additive (Diamond V, Original XPC®) on the colonization of cecal and ovarian tissues of commercial pullets directly and indirectly exposed to Salmonella Enteritidis (SE). Four hundred and eighty commercial, day-of-age W-36 chicks were randomly allotted to 60 cages per treatment in two identical BSL-2 isolation rooms (Iowa State University) with four birds per cage and fed control (CON) or treatment (TRT) diets for the duration of study. At 16 weeks, two birds per cage were directly challenged via oral gavage with 1.1 × 109 CFU of a nalidixic-acid-resistant SE strain. The remaining two birds in each cage were thus horizontally exposed to the SE challenge. At 3, 7, and 14 days post-challenge (DPC), 20 cages per group were harvested and sampled for SE prevalence and load. No significant differences were observed between groups for SE prevalence in the ceca or ovary tissues of directly challenged birds. For the indirectly exposed cohort, SE cecal prevalence at 7 DPC was significantly lower for TRT (50.0%) vs. CON (72.5%) (p = 0.037) and, likewise, demonstrated significantly lower mean SE cecal load (1.69 Log10) vs. CON (2.83 Log10) (p = 0.005). At 14 DPC, no significant differences were detected but ~10% fewer birds remained positive in the TRT group vs. CON (p > 0.05). These findings suggest that diets supplemented with SCFP postbiotic may be a useful tool for mitigating SE colonization in horizontally exposed pullets and may support pre-harvest food-safety strategies. [ABSTRACT FROM AUTHOR]

A series of substituted N‐(2‐Morpholinoethyl)‐3‐phenylquinoxalin‐2‐amines (5a–j) (5ab, 5ac) were synthesized in good yield and characterized for their structural confirmation. The pure quinoxaline products were screened for their in‐vitro antibacterial activity against Salmonella paratyphi, a well‐known food borne pathogen. The preliminary results revealed that among the series, compounds 5a, 5c, 5d, 5e, 5f, 5h, 5ab and 5ac bearing bromo, fluoro, methoxy, methyl groups at para position on phenyl ring which inturn substituted at third position of quinoxaline and methyl, benzoyl groups at sixth position on the quinoxaline were emerged as potential candidates by displaying antisalmonella activity. Among the potential candidates, compounds 5c, 5e, 5f and 5ac were effective against Salmonella whereas compounds 5a, 5f and 5ac effectively inhibited the biofilm formation of Salmonella. [ABSTRACT FROM AUTHOR]

Background: Non-typhoidal Salmonella (NTS) is a major foodborne zoonotic pathogen worldwide. In the current study, Various NTS strains were isolated from (cows, milk and dairy products in addition to humans) in New Valley and Assiut Governorate, Egypt. NTS were firstly serotyped and tested by antibiotic sensitivity test. Secondly, some virulence genes and Antibiotic resistance genes have been identified by using PCR. Finally, Phylogenesis was performed depending on the invA gene, for two S. typhimurium isolates (one of animal origin and the other of human origin for evaluating zoonotic potential). Results: Out of 800 examined samples, the total number of isolates was 87 (10.88%), which were classified into 13 serotypes, with the most prevalent being S. Typhimurium and S. enteritidis. Both bovine and human isolates showed the highest resistance to clindamycin and streptomycin, with 90.80% of the tested isolates exhibiting MDR. The occurrence of the invA gene was 100%, while 72.22%, 30.56%, and 94.44% of the examined strains were positive for stn, spvC, and hilA genes, respectively. Additionally, blaOXA-2 was detected in 16.67% (6/ 36) of the tested isolates, while blaCMY-1 was detected in 30.56% (11of 36) of the tested isolates. Phylogenesis revealed a high degree of similarity between the two isolates. Conclusions: The high occurrence of MDR strains of NTS in both human and animal samples with high degree of genetic similarity, shows that cows, milk and milk product may be a valuable source of human infection with NTS and interfere with treatment procedures. [ABSTRACT FROM AUTHOR]

There is growing pressure to find a way to eradicate or reduce the levels of foodborne pathogens such as Campylobacter in broiler chickens, whilst limiting the use of antimicrobials. For Campylobacter, there is currently no vaccine and on-farm biosecurity alone is insufficient to prevent colonization of broiler chicken flocks. Dipteran flies are proven carriers of Campylobacter and their entry into broiler houses may contribute to its transmission to broiler chickens. As there is currently no experimental vector transmission model for Campylobacter and chickens, we decided to examine experimentally whether Galleria mellonella could be used as vector to transmit Campylobacter to broiler chickens. More recently, the use of live insect feed has been proposed both for its nutritional qualities and improving bird welfare through the encouragement of natural foraging behaviours and it is unclear any risk this poses in terms of pathogen transmission. In this study, day-old chicks (n = 29) were obtained from a commercial hatchery. At three weeks of age, birds were split into 4 This groups; Group 1 was infected via oral gavage with 106 cells of C. jejuni-M1, Group 2 was fed Galleria mellonella infected with 106 cells of C. jejuni-M1, Group 3 was fed uninfected Galleria mellonella, whilst the remaining group was unchallenged. Cloacal swabs were taken at 2, 4, and 6 days post-infection (dpi) to follow transmission and at 8 dpi birds culled and C. jejuni load quantified in the caeca and liver. At 8 dpi, all birds in both the Campylobacter gavage group and those in the group fed the Campylobacter infected Galleria mellonella were Campylobacter positive, whereas those fed uninfected Galleria mellonella and the control group were all Campylobacter negative. The mean caecal Campylobacter load in the Campylobacter gavage group was 1.7 × 1010 per gram compared with 8.6 × 109 in the group fed the Campylobacter-infected Galleria mellonella. No liver positives were found in any of the groups. Our findings indicate that feeding broiler chickens with the vector Galleria mellonella infected with C. jejuni-M1 is sufficient to establish colonisation with C. jejuni. We propose that Galleria can be used as an easy and flexible model for vector transmission of foodborne pathogens in chicken. [ABSTRACT FROM AUTHOR]

1. This study evaluated the minimal inhibitory concentration (MIC) of ciprofloxacin and the presence of plasmid-mediated quinolone resistance (PMQR) mechanisms in 97 nontyphoidal Salmonella spp. isolated from broilers and carcases from three different regions in Brazil. The presence of mutations in quinolone resistance determination regions (QRDRS) was investigated in the ciprofloxacin-resistant strain by DNA sequencing. 2. Most of the Salmonella spp. (85.6%) had intermediate resistance to ciprofloxacin and only one isolate was resistant. MIC breakpoints ranged from ≤0.03 to 1 µg/ml and 67.0% of the strains had a MIC of 0.25 µg/ml (n=65). Thirteen strains (13.4%) were susceptible to ciprofloxacin with MIC ≤0.06 µg/ml. The qnrB gene was detected in eight isolates with intermediate resistance and in two susceptible strains. The other PMQR genes, qnrA, qnrC, qnrD, qnrS, qnrVC, aac(6′)-Ib, qepA, oqxAB and mutations in QRDR were not detected in any strain. 3. There was a high frequency of ciprofloxacin intermediate resistant Salmonella from broiler and broiler carcases from Brazil. The presence of these strains in poultry and derived products poses a risk to public health. [ABSTRACT FROM AUTHOR]

Bacteriophages, which specifically infect and kill bacteria, are currently used as additives to control pathogens such as Salmonella in human food (PhageGuard S®) or animal feed (SalmoFREE®, Bafasal®). Indeed, salmonellosis is among the most important zoonotic foodborne illnesses. The presence of anti-phage defenses protecting bacteria against phage infection could impair phage applications aiming at reducing the burden of foodborne pathogens such as Salmonella enterica subsp. enterica serovar Typhimurium (S. Typhimurium) to the food industry. In this study, the landscape of S. Typhimurium anti-phage defenses was bioinformatically investigated in publicly available genomes using the webserver PADLOC. The primary anti-phage systems identified in S. Typhimurium use nucleic acid degradation and abortive infection mechanisms. Reference systems were identified on an integrative and conjugative element, a transposon, a putative integrative and mobilizable element, and prophages. Additionally, the mobile genetic elements (MGEs) containing a subset of anti-phage systems were found in the Salmonella enterica species. Lastly, the MGEs alone were also identified in the Enterobacteriaceae family. The presented diversity assessment of the anti-phage defenses and investigation of their dissemination through MGEs in S. Typhimurium constitute a first step towards the design of preventive measures against the spread of phage resistance that may hinder phage applications. [ABSTRACT FROM AUTHOR]

Rabbit meat and offal are considered valuable sources of high biological value animal protein. Rabbit meat is rich in essential amino acids, low in cholesterol, and contains considerable amounts of trace elements such as calcium, magnesium, and zinc. However, the potential contribution of rabbit meat and offal in the transmission of foodborne pathogens such as Staphylococcus aureus (S. aureus) and Salmonella spp. is neglected. Therefore, this study was conducted first to investigate the prevalence rates of S. aureus and Salmonella spp. in the retailed rabbit meat at Sharkia Governorate, Egypt. Second, serological identification of the isolated bacteria was followed. Detection of S. aureus-enterotoxins and Salmonella-virulence-associated genes was also done using PCR. Antimicrobial susceptibility testing of the recovered bacterial isolates was additionally examined. The acquired results showed that 17% of the investigated samples of rabbit meat contained S. aureus. Where S. aureus was isolated from the investigated rabbit’s breast, thigh, liver, and kidney at 20%, 24%, 12%, and 12% of each, respectively. Salmonella spp. was isolated at 13%. Salmonella spp. was isolated from the investigated rabbit thigh, liver, breast, and kidney at 16%, 16%, 12%, and 8%, respectively. Four different strains of Salmonella spp namely, S. Typhimurium, S. Kentucky, S. Virchow, and S. Infantis were recovered in the current study. The recovered S. aureus and Salmonella spp. harbored enterotoxins and virulence attributes with multidrug resistance. Therefore, strict hygienic measures should be followed during the processing and handling of rabbit meat and offal. [ABSTRACT FROM AUTHOR]

Chicken meat products represent an important source of animal derived proteins, vitamins, and minerals. However, chicken meat products might act as potential sources of human exposure to foodborne pathogens such as Staphylococcus aureus (S. aureus) and Salmonella species. The objectives of the present study were first to investigate the prevalence rates of S. aureus and Salmonella species in the retailed chicken meat products at Zagazig city, Egypt. Second, serological identification of the isolated bacteria was followed. Third, screening of S. aureus enterotoxin coding genes (sea seb, and sed) as well as Salmonella virulence associated genes including invA, Salmonella hyper-invasive locus (hilA), and Salmonella enterotoxin (stn) was done using PCR. The obtained results revealed isolation of S. aureus from the examined chicken meat products at 22%, and Salmonella spp., at 6.66%. Where S. aureus was isolated at 33.33%, 36.66%, 13.33%, 6.66%, and 20% from the examined chicken burger, fillet, luncheon, nuggets, and panne, respectively. Salmonella spp. could be isolated only from chicken burger and fillet at 10%, and 23.33%, respectively. The recovered S. aureus isolates harbored enterotoxin coding genes (sea, and seb). Likely the recovered Salmonella spp. isolates harbored virulence associated genes such as invA, hilA, and stn. Moreover, antimicrobial sensitivity testing of the recovered isolates showed multidrug resistance profiling. In conclusion, chicken meat products retailed in Egypt might be potential sources for the spread of multidrug resistant S. aureus and Salmonella spp. Therefore, strict hygienic measures should be adopted during manufacturing of such meat products. [ABSTRACT FROM AUTHOR]

Salmonella is one of the most widely distributed and harmful food-borne pathogens; thus, the rapid detection of viable Salmonella is important for ensuring food safety. In this study, a rapid visual strategy based on loop-mediated isothermal amplification (LAMP) with the addition of thermal inorganic pyrophosphatase and linked with an ammonium molybdate chromogenic buffer was established to detect Salmonella. Specific primers were designed based on the phoP gene of Salmonella spp. The pyrophosphatase concentration, LAMP time, addition of ammonium molybdate chromogenic buffer, and color reaction time were optimized. Based on the optimal conditions, the sensitivity and specificity of the method were examined. In addition, the ability to detect actual samples was verified using apple juice containing Salmonella. LAMP was performed at 65°C for 45 min in the presence of thermal inorganic pyrophosphatase at a final concentration of 4 U ml−1, and 20 μl of the LAMP product was reacted with 50 μl of phosphate chromogenic buffer at 25°C for 15 min. According to our results, the limit of detection of the LAMP assay for viable Salmonella was 1.83 × 102 CFU per reaction, and nonspecific amplification was not observed. The detection rates of Salmonella Typhimurium with different concentrations in apple juice were 89.11%–94.80%, which verifies that the visual detection strategy is suitable for actual sample detection. [ABSTRACT FROM AUTHOR]

Background: Salmonella are pathogenic foodborne bacteria with complex pathogenicity from numerous virulence genes housed in Salmonella pathogenicity islands (SPIs), plasmids, and other gene cassettes. However, Salmonella virulence gene distributions and mechanisms remain unestablished. In the Philippines, studies mainly report Salmonella incidences and antimicrobial resistance, but little to none on virulence profiles, their associations to animal sources, collection sites and Salmonella serogroups. Hence, a total of 799 Salmonella isolates, previously obtained from pig, cow, and chicken meat samples in wet markets and abattoirs (wet markets: 124 chicken, 151 cow, and 352 pig meat isolates; abattoirs: 172 pig tonsil and jejunum isolates) in Metro Manila, Philippines, were revived and confirmed as Salmonella through invA gene polymerase chain reaction (PCR). Isolates were then screened for eight virulence genes, namely avrA, hilA, sseC, mgtC, spi4R, pipB, spvC and spvR, by optimized multiplex PCR and significant pair associations between virulence genes were determined through Fisher's exact test. Gene frequency patterns were also determined. Salmonella serogroups in addition to animal sources and location types were also used to predict virulence genes prevalence using binary logistic regression. Results: High frequencies (64 to 98%) of SPI virulence genes were detected among 799 Salmonella isolates namely mgtC, pipB, avrA, hilA, spi4R and sseC, from most to least. However, only one isolate was positive for plasmid-borne virulence genes, spvC and spvR. Diversity in virulence genes across Salmonella serogroups for 587 Salmonella isolates (O:3 = 250, O:4 = 133, O:6,7 = 99, O:8 = 93, O:9 = 12) was also demonstrated through statistical predictions, particularly for avrA, hilA, sseC, and mgtC. mgtC, the most frequent virulence gene, was predicted by serogroup O:9, while sseC, the least frequent, was predicted by serogroup O:4 and chicken animal source. The highest virulence gene pattern involved SPIs 1-5 genes which suggests the wide distribution and high pathogenic potential of Salmonella. Statistical analyses showed five virulence gene pair associations, namely avrA and hilA, avrA and spi4R, hilA and spi4R, sseC and spi4R, and mgtC and pipB. The animal sources predicted the presence of virulence genes, sseC and pipB, whereas location type for hilA and spi4R, suggesting that these factors may contribute to the type and pathogenicity of Salmonella present. Conclusion: The high prevalence of virulence genes among Salmonella in the study suggests the high pathogenic potential of Salmonella from abattoirs and wet markets of Metro Manila, Philippines which poses food safety and public health concerns and threatens the Philippine food animal industry. Statistical associations between virulence genes and prediction analyses across Salmonella serogroups and external factors such as animal source and location type and presence of virulence genes suggest the diversity of Salmonella virulence and illustrate determining factors to Salmonella pathogenicity. This study recommends relevant agencies in the Philippines to improve standards in food animal industries and increase efforts in monitoring of foodborne pathogens. [ABSTRACT FROM AUTHOR]

Simple Summary: Salmonella spp. is a major foodborne pathogen responsible for salmonellosis in animals and humans. The gastrointestinal tracts of reptiles and amphibians have been described as a source of Salmonella transmission, and the main outbreaks that have been reported occurred after contact with infected animals as pets or after the ingestion of their meat. The aim of this study was to determine the presence of 24 virulence genes and characterize the genotypic antibiotic resistance profile in Salmonella strains isolated from Caiman crocodilus fuscus obtained in situ (natural habitat) in Prado, Tolima, (Colombia) in a previous study. Fifteen Salmonella strains were obtained from Caiman crocodilus fuscus, where all the strains have 3 out of 26 resistances genes and 19 out of 24 virulence genes. The results indicate that Colombian babilla (Caiman crocodilus fuscus) may have a role as a carrier of multidrug resistant bacteria. Salmonella enterica is a pathogen capable of colonizing various environments, including the intestinal tract of different animals such as mammals, birds, and reptiles, which can act as carriers. S. enterica infection induces different clinical diseases, gastroenteritis being the most common, which in some cases, can evolve to septicemia and meningitis. Reptiles and amphibians have been reported as a reservoir of Salmonella, and transmission of the pathogen to humans has been documented. This study aimed to determine the presence of virulence genes and characterize the genotypic antibiotic resistance profile in Salmonella strains isolated from Caiman crocodilus fuscus obtained in situ (natural habitat) in Prado, Tolima, Colombia in a previous study and stored in a strain bank in our laboratory. Fifteen Salmonella strains were evaluated through endpoint PCR to determine the presence of resistance genes and virulence genes. The genes blaTEM, strB, and sul1 were detected in all the strains that confer resistance to ampicillin, streptomycin, and sulfamethoxazole, as well as the virulence genes invA, pefA, prgH, spaN, tolC, sipB, sitC, pagC, msgA, spiA, sopB, sifA, lpfA, csgA, hilA, orgA, iroN, avrA, and sivH, indicating the possible role of babilla (Caiman crocodilus fuscus) as a carrier of multidrug-resistant bacteria. [ABSTRACT FROM AUTHOR]

Summary: Developing rapid detection tools and methods for foodborne pathogens has always been a research hotspot, which is undoubtedly very important for food safety. In this study, the preparation of functional magnetic nanoprobes and their application to detect target pathogens in a complex matrix by low‐field nuclear magnetic resonance (LF‐NMR) is demonstrated. The long‐arm functional magnetic nanoprobes were constructed by modification with polyethylene glycol (PEG) onto carboxyl‐modified magnetic nanoparticles (MNPs) and then reaction with biotin (Bio). Under the optimal conditions, the lower limit that can be detected in the PBS buffer system is 100 CFU/mL, and the detection of the actual sample matrix can be achieved 102 CFU/g. The practical application of LF‐NMR sensors to detect harmful pathogenic bacteria in food provides an efficient way of monitoring dangerous pathogenic diseases. [ABSTRACT FROM AUTHOR]

Research in green synthesis of metallic nanoparticles and their applications in engineering, food, biomedicine and agriculture is growing rapidly. The presence of biologically active metabolites in fungi makes them ideal candidates for green synthesis of silver nanoparticles (AgNPs). This study aims at discerning an emerging applicability of a basidiomycete mushroom, Phaeolus schweinitzii, for mycosynthesis of AgNPs and their antimicrobial properties. The colour change in P. schweinitzii aqueous extract was used to detect and curate the synthesis of AgNPs. The AgNP surface plasmon resonance (SPR) was observed in the visible spectra at approximately 428 nm using UV-Vis spectroscopy. The XRD spectrum revealed a face-centered cubic (FCC) structure of AgNPs with an average crystallite size of 38.78 nm. FT-IR manifested various functional clusters of biomolecules which were involved in bioreduction, capping and stabilization of AgNPs. FE-SEM imaging of AgNPs revealed a spherical shape with an average size of 88.65 nm. The synthesized AgNPs showed strong antimicrobial activities against Salmonella gallinarum, E. coli, Staphylococcus aureus, Aspergillus niger and Fusarium oxysporum with varying zones of inhibition at different concentrations. The highest concentration (5 mg/ml) of AgNPs produced a maximum zone of inhibition (1 3. 3 3 ± 0. 5 7 mm) against gram negative bacteria (Salmonella gallinarum and E. coli) and lowest (1 1. 6 6 ± 0. 5 7 mm) against gram positive bacteria (Staphylococcus aureus). The study also revealed that synthesized AgNPs showed comparatively higher antifungal activity than the positive control (nystatin). The findings from this study explicitly concur with the ever-relevant use of biogenic AgNPs against various pathogenic microorganisms. AgNPs were successfully synthesized using fungal aqueous extract and characterized by various analytical techniques. Biosynthesized AgNPs showed significant growth inhibition of different bacterial and fungal pathogens under test, which infer their application for various biomedical purposes, as well as for food packaging to reduce contamination and enhance long-term storage and preservation of foods. Metal-based nanoparticles such as silver nanoparticles may prove to be very beneficial in the agricultural sector, such as their use as nanopesticides. [ABSTRACT FROM AUTHOR]

Salmonella spp. are one of the most frequently reported foodborne pathogens worldwide. The present study investigated the virulence genotypes and antimicrobial sensitivity of Salmonella spp. isolated from broiler chickens in Kafr El-Sheikh governorate, Egypt. A total of 180 samples [liver (n=70), spleen (n=70) and caecum (n=40)] collected from 50 different broiler chicken flocks were used to isolate Salmonellae. All suspected samples were examined through a series of conventional bacteriological, biochemical, and serological techniques for isolation and identification of Salmonella spp. All isolates were tested for susceptibility to 16 antimicrobials. Virulence factors were determined using the polymerase chain reaction assays targeting the invA, pefA, avrA, sopB and spvC. The overall isolation percentage of Salmonella was 6.1%. Eleven Salmonella isolates belonging to four different serovars were recovered. S. Belgdam was the most predominant species (7/11, 63.6%), followed by S. Typhimurium (2/11, 18.2%), and S. Virchow and Salmonella enterica subsp. Salamae (S. Salamae) (1/11, 9.1% each). All the isolates were positive for all tested genes except S. Salamae, which harbored neither the sopB nor avrA genes. All isolates exhibited resistance to almost all antimicrobials used. The finding of the present study show high positivity of virulence genes as well as multidrug resistance of all serotypes suggesting pathogenic Salmonella strains. [ABSTRACT FROM AUTHOR]

Salmonella spp. is the causative agent of salmonellosis outbreaks in poultry and meats, but recent studies have implicated this pathogen in foodborne outbreaks associated with vegetables. Salmonellosis is commonly managed with antibiotics, but antimicrobial resistance has complicated the treatment of the disease. The pathogenesis of Salmonella spp. is based on virulence factors such as plasmid-encoded genes and lipopolysaccharide moieties, which can be detected by PCR and serotyping, respectively. Thirteen (13) isolates previously identified and confirmed as Salmonella spp. using invA gene-targeting assay were isolated from onion leaf samples collected from wet markets in Metro Manila, Philippines. The isolates were characterized based on the presence of plasmid-encoded virulence gene, serogroup and serotype, and antibiotic resistance profiles using the VITEK®2 system. All 13 Salmonella spp. isolates were spvC-negative. O-serotyping revealed the presence of isolates belonging to serogroups C1 (30.8%), C2 (23.0%), and E1 (30.8%). Two isolates (15.4%) did not belong to the serogroups examined in the study. Further, sequence analysis revealed the presence of serovars Newport, Weltevreden, Tennessee, and Anatum. All the isolates were resistant to at least five antimicrobial agents. To our knowledge, this is the first study in the Philippines to establish baseline data for the molecular features and antibiogram profiles of Salmonella spp. isolated in onion leaf samples from selected wet markets in Metro Manila, Philippines. Furthermore, this study is the first report on the occurrence of four different Salmonella serovars from onion leaves. The data obtained in this study could be used as baseline information and guidance in the implementation of the GAP, monitoring programs of the Department of Agriculture, and the formulation of laws and regulations by policymakers that will address safety issues in fresh produce and quality management principles in farm operations. [ABSTRACT FROM AUTHOR]

Salmonella is a crucial food‐borne pathogen causing food poisoning, leading to severe public health events. Here, we developed a technique by integrating recombinase polymerase amplification with CRISPR‐LbCas12a and employing two targets with engineered crRNA for detection of Salmonella (RPA‐LbCas12a‐TTECDS). Our findings revealed that this novel method rapidly detects trace Salmonella in food through fluorescence intensity and provides a template for other food‐borne pathogen detection methods. Further, crRNA was optimized to increase detection sensitivity. Double targets were used to enhance the detection accuracy, reaching the level of qPCR, which was superior to fluorescent RPA. The RPA‐LbCas12a‐TTECDS system specifically detected Salmonella levels as low as 50 CFU per ml at 37°C in 1 h. In summary, a simple, rapid, sensitive and high accuracy detection technique based on CRISPR‐Cas12a was created for Salmonella detection without complicated equipment. Significance and Impact of the Study: The emergence of CRISPR‐Cas12a provides a new technique for detection methods. In this study, we developed a rapid, sensitive, and high accuracy RPA‐LbCas12a‐TTECDS based toolbox for Salmonella detection. This method is easy to operate with a completion span of 50 min by a fluorescence detector. The simple and quick‐to‐read method is potentially useful as point‐of‐care testing for Salmonella. [ABSTRACT FROM AUTHOR]

Salmonella and Escherichia coli are important foodborne pathogens, forming bacterial biofilms that contribute to their virulence, antimicrobial resistance, and survival on surfaces. Broad lytic phages are promising alternatives to conventional technologies for pathogen biocontrol and reducing biofilms. Herein, we isolated and characterized a novel polyvalent phage STP55 that not only lyse some serotypes of Salmonella, but also some E. coli strains. It had a wide range of pH (4–12) and thermal (30–60 °C) tolerances. The latent time was determined to be 10 min in the one-step growth experiment. Morphological observations by transmission electron microscopy and phylogenetic analysis using terminase gene classified STP55 to family Ackermannviridae in the order Caudovirales, with a complex tail structure. The genome was found to comprise 157,708 bp double-stranded DNA, with 44.57% GC content, 207 predicted ORFs and with no genes associated with antibiotic resistance, toxins, lysogeny, and virulence factors. Particularly, phage STP55 was able to inhibit single- and dual-species biofilms formation by S. Typhimurium ATCC 14028 and E. coli O157: H7, with a reduction percentage of 51.0%, 47.8% and 52.8%, respectively. Moreover, more than 65.0%, 72.9% and 46.2% of an established, single- and dual-species biofilms by S. Typhimurium ATCC 14028 and E. coli O157: H7 were removed after 8 h exposure to the phage STP55, respectively. The elimination effect of STP55 on dual-species biofilm formed on lettuce was further observed by SEM. Overall, our results demonstrated that STP55 is a promising antimicrobial against Salmonella and E. coli. [ABSTRACT FROM AUTHOR]

Simple Summary: Salmonella and Campylobacter are two of the most common foodborne pathogens isolated from poultry meat. Over the years, a number of advancements have been made in poultry processing to reduce the prevalence of these pathogens, such as the utilization of peracetic acid in various processing steps. However, despite these efforts, Salmonella and Campylobacter continue to persist in retail broiler meat products. In an effort to characterize the efficacy of existing peracetic acid antimicrobial interventions in the industry, we collected broiler meat samples from throughout the processing chain and from different commercial poultry processing plants. Our results suggest that antimicrobial spray cabinets demonstrate little efficacy in reducing the prevalence of these pathogens. However, the utilization of peracetic acid in carcass chilling tanks remains the most effective chemical intervention. An increase in prevalence during second processing and MDM production suggests that cross-contamination still plays a pivotal role in broiler meat contamination at the retail level. In poultry processing, Salmonella and Campylobacter contaminations are major food safety concerns. Peracetic acid (PAA) is an antimicrobial commonly used in commercial poultry processing to reduce pathogen prevalence so as to meet the USDA-FSIS performance standards. The objective of this study was to determine the prevalence of Salmonella and Campylobacter on broiler meat in various steps of commercial poultry processing in plants that use PAA. Post-pick, pre-chill, post-chill, and drumstick chicken samples were collected from three processing plants and mechanically deboned meat (MDM) was collected from two of the three plants. Each plant was sampled thrice, and 10 samples were collected from each processing step during each visit. Among the 420 samples, 79 were contaminated with Salmonella and 155 were contaminated with Campylobacter. Salmonella and Campylobacter contamination on the post-pick samples averaged 32.2%. Significant reductions in Salmonella and Campylobacter were observed in pre-chill to post-chill samples, where the prevalence was reduced from 34% and 64.4% to nondetectable limits and 1.1%, respectively (p < 0.001). Salmonella and Campylobacter remained undetectable on the drumstick samples in all three processing plants. However, the prevalence of Salmonella and Campylobacter on MDM was similar to the post-pick prevalence, which suggests substantial cross-contamination from post-chill to MDM. [ABSTRACT FROM AUTHOR]

Food production facilities are often routinely tested over time for the presence of foodborne pathogens (e.g., Listeria monocytogenes or Salmonella enterica subsp. enterica). Strains detected in a single sampling event can be classified as transient; positive findings of the same strain across multiple sampling events can be classified as resident pathogens. We analyzed whole-genome sequence (WGS) data from 4,758 isolates (L. monocytogenes = 3,685; Salmonella = 1,073) from environmental samples taken by FDA from 536 U.S. facilities. Our primary objective was to determine the frequency of transient or resident pathogens within food production facilities. Strains were defined as isolates from the same facility that are less than 50 SNP (single-nucleotide polymorphisms) different from one another. Resident pathogens were defined as strains that had more than one isolate collected >59 days apart and from the same facility. We found 1,076 strains (median = 1 and maximum = 21 strains per facility); 180 were resident pathogens, 659 were transient, and 237 came from facilities that had only been sampled once. As a result, 21% of strains (180/ 839) from facilities with positive findings and that were sampled multiple times were found to be resident pathogens; nearly 1 in 4 (23%) of L. monocytogenes strains were found to be resident pathogens compared to 1 in 6 (16%) of Salmonella strains. Our results emphasize the critical importance of preventing the colonization of food production environments by foodborne pathogens, since when colonization does occur, there is an appreciable chance it will become a resident pathogen that presents an ongoing potential to contaminate product. [ABSTRACT FROM AUTHOR]

The development of cost-effective, portable, and ease-of-use sensing system for on-site genetic diagnostics is highly desirable for pathogen screening and infectious disease diagnosis. This study develops (1) a paper-based biochip which is able to integrate the loop-mediated isothermal amplification (LAMP) protocols for simultaneous detection of Escherichia coli O157:H7, Salmonella spp., and Staphylococcus aureus, and (2) a stand-alone smartphone-based portable device which can control exactly 65 °C for isothermal amplification as well as collect and analyze the thus generated fluorescence signals. The reported sensing system has been successfully demonstrated for foodborne pathogen detection with a limit of detection of 2.8 × 10−5 ng μL−1. Spiked milk samples with concentration as low as 10 CFU mL−1 were successfully determined within 4 h, demonstrating the practicality of the reported sensing system in the fields. The reported sensing system featuring simplicity and reliability is ideally suited for genetic diagnostics in low resource settings. [ABSTRACT FROM AUTHOR]