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Salmonella enterica can cause intestinal or systemic infections in humans and animals mainly by the presence of pathogenicity islands SPI-1 and SPI-2, containing 39 and 44 genes, respectively. The AraC-like regulator HilD positively controls the expression of the SPI-1 genes, as well as many other Salmonella virulence genes including those located in SPI-2. A previous report indicates that the two-component system CpxR/A regulates the SPI-1 genes: the absence of the sensor kinase CpxA, but not the absence of its cognate response regulator CpxR, reduces their expression. The presence and absence of cell envelope stress activates kinase and phosphatase activities of CpxA, respectively, which in turn controls the level of phosphorylated CpxR (CpxR-P). In this work, we further define the mechanism for the CpxR/A-mediated regulation of SPI-1 genes. The negative effect exerted by the absence of CpxA on the expression of SPI-1 genes was counteracted by the absence of CpxR or by the absence of the two enzymes, AckA and Pta, which render acetyl-phosphate that phosphorylates CpxR. Furthermore, overexpression of the lipoprotein NlpE, which activates CpxA kinase activity on CpxR, or overexpression of CpxR, repressed the expression of SPI-1 genes. Thus, our results provide several lines of evidence strongly supporting that the absence of CpxA leads to the phosphorylation of CpxR via the AckA/Pta enzymes, which represses both the SPI-1 and SPI-2 genes. Additionally, we show that in the absence of the Lon protease, which degrades HilD, the CpxR-P-mediated repression of the SPI-1 genes is mostly lost; moreover, we demonstrate that CpxR-P negatively affects the stability of HilD and thus decreases the expression of HilD-target genes, such as hilD itself and hilA , located in SPI-1. Our data further expand the insight on the different regulatory pathways for gene expression involving CpxR/A and on the complex regulatory network governing virulence in Salmonella. [ABSTRACT FROM AUTHOR]

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Background: Colistin is commonly used as a last-resort antibiotic for multidrug resistance (MDR) bacterial infections. The emergence of colistin-resistant (CL-R) Salmonella has become a significant public health concern. However, the prevalence of CL-R Salmonella in Guizhou province remains unknown. Therefore, it is necessary to monitor CL-R Salmonella in Guizhou and systematically elucidate their characteristics-related resistance, virulence, and molecular epidemiology to develop effective public health strategies against resistant pathogens. Methods: The CL-R Salmonella isolates were identified from 933 Salmonella isolates by antimicrobial resistance testing. To further evaluate the molecular epidemiology, the CL-R Salmonella isolates underwent whole-genome sequencing (WGS) analysis followed by bioinformatic analysis. Results: A total of 43 CL-R isolates (4.6%) were identified from 933 Salmonella isolates, of which 39 isolates being MDR (resistance to three or more classes of antimicrobials). WGS analysis revealed 34 antibiotic resistance genes (ARGs), and point mutations in the gyrA gene (D87Y and D87G) were identified in all 43 CL-R isolates. Only one isolate carried the mcr-1.1 gene, a known colistin resistance. All CL-R isolates were found to carry multidrug efflux pumps. Furthermore, the most common resistance gene was aac(6′)-ly (40 out of 43), followed by blaTEM-1 (39 out of 43). The majority of CL-R isolates contained the virulence factor spvB and a notable diversity in other virulence factors with varied functions. Core genome multilocus sequence typing (cgMLST) revealed that 43 CL-R Salmonella isolates were divided into 19 cgSTs, with cgST179151 (10 out of 43) being the most prevalent. Additionally, the CL-R Salmonella isolates exhibited genetic similarities with human Salmonella isolates from Poland, Canada, and Zhejiang province. Among the 42 CL-R isolates lacking markers for CL-R, 12 single-nucleotide variations (SNVs) were observed in 24 isolates using genome-wide association study (GWAS) analysis, which was possibly associated with colistin resistance. Conclusion: This study revealed that the majority of CL-R Salmonella isolates in Guizhou province exhibited MDR, with complex resistance mechanisms, representing a significant public health challenge. The genetic similarities between isolates from Guizhou and other regions suggested the possibility of international transmission or shared reservoirs of resistance. These results highlighted the urgent need for enhanced surveillance and effective public health strategies to address the risks posed by these pathogens in Guizhou. [ABSTRACT FROM AUTHOR]

Background: Salmonella is a leading cause of human acute bacterial gastroenteritis worldwide. Outbreaks of human salmonellosis have often been associated with consumption of contaminated poultry products. Various strategies have been explored to control this microorganism during poultry production and processing. Vaccination of broiler chickens is regarded as one of the effectives means to control this microorganism. The aim of the present study was to compare the epitope identification in the Salmonella enterica serotype Heidelberg FlgK protein by in silico prediction and in vivo experiment with mass spectrometry in association with immunoprecipitation proteomics. Results: The Salmonella serotype Heidelberg FlgK protein contains 553 amino acids with a molecular mass of 61 kDa. This protein is conserved among Salmonella serotype Heidelberg isolates. The results show that both approaches identified three common shared consensus peptide epitope sequences at the positions of 77–95, 243–255 and 358–373 in the Salmonella serotype Heidelberg FlgK protein. Conclusions: These findings provide a rational for further evaluation of these shared linear epitopes in vaccine development to cover the chicken population. [ABSTRACT FROM AUTHOR]

Introduction: Salmonella is a common foodborne pathogenic bacterium, displaying facultative intracellular parasitic behavior, which can help the escape against antibiotics treatment. Bacteriophages have the potential to control both intracellular and facultative intracellular bacteria and can be developed as antibiotic alternatives. Methods: This study isolated and characterized vB-SeS-01, a novel Guernseyvirinae phage preying on Salmonella enterica , whose genome is closely related to those of phages SHWT1 and vB-SenS-EnJE1. Furthermore, nine phage-carrying liposome formulations were developed by film hydration method and via liposome extruder. Results and Discussion: Phage vB-SeS-01 displays strong lysis ability against 9 out of 24 tested S. enterica strains (including the pathogenic "Sendai" and "Enteritidis" serovars), high replicability with a burst size of 111 ± 15 PFU/ cell and a titre up to 2.1 × 1011 PFU/mL, and broad pH (4.0 ~ 13.0) and temperature (4 ~ 80°C) stabilities. Among the nine vB-SeS-01 liposome-carrying formulations, the one encapsulated with PC:Chol:T80:SA = 9:1:2:0.5 without sonication displayed the optimal features. This formulation carried up to 1011 PFU/mL, with an encapsulation rate of 80%, an average size of 172.8 nm, and a polydispersity index (PDI) of 0.087. It remained stable at 4°C and 23°C for at least 21 days and at 37°C for 7 days. Both vB-SeS-01 and vB-SeS-01-loaded liposomes displayed intracellular antimicrobial effects and could reduce the transcription level of some tested intracellular inflammatory factors caused by the infected S. enterica sv. Sendai 16,226 and Enteritidis 50041CMCC. [ABSTRACT FROM AUTHOR]

One of the challenges of microbiological testing is the complex and lengthy sample preparation, causing delays in getting the final result. Immunomagnetic separation is one of the sample preparation techniques recently used to overcome this complexity. However, it is expensive, fragile, and requires cold storage. This study aimed to use chitosan-coated magnetic nanoparticles (cMNP) to capture bacterial cells from a simulated matrix and understand the interaction between the bacteria and the cMNP using batch adsorption studies. To illustrate the concept, Salmonella Enteritidis and Escherichia coli were used. Results showed that the adsorption of Salmonella Enteritidis and E. coli fitted the pseudo-second-order kinetic model (R2 = 0.939 and 0.968, respectively) and the Freundlich isotherm model (R2 = 0.999 and 0.970, respectively). The increased ionic strength enhanced bacterial adsorption, and the highest capture efficiency was observed at pH 4 (32.8% and 98.1% for Salmonella Enteritidis and E. coli, respectively). These results show that chemisorption plays a significant role in bacterial adsorption to cMNP. Furthermore, increasing ionic strength and acidic pH (pH 4) significantly affects the adsorption of Salmonella Enteritidis and E. coli on cMNP, making them crucial for enhancing the performance of cMNP-based sample preparation methods. [ABSTRACT FROM AUTHOR]

Background: Companion animals, like household dogs, are an overlooked transmission point for zoonotic pathogens such as nontyphoidal Salmonella (NTS). Given the proximity of dogs to humans and the use of critically important antibiotics in companion animal medicine, household dogs represent a risk for the spread of antimicrobial‐resistant (AMR) Salmonella. Methods and Results: To this end, we aimed to leverage existing biosurveillance infrastructure to investigate AMR and the zoonotic potential of NTS isolated from dogs and humans. We identified all NTS strains isolated from domestic dogs via the Veterinary Laboratory Investigation and Response Network between May 2017 and March 2023 (N = 87), and spatiotemporally matched strains isolated from humans in the NCBI Pathogen Isolate Browser (N = 77). These 164 strains, collected from 17 states in the United States, formed the basis of our analysis. Strains isolated from dogs comprised diverse serovars, with most being clinically relevant to human health. All strains possessed AMR determinants for drug classes deemed critically or highly important by the World Health Organization. We identified sixteen NTS isolates from humans closely related to ≥1 of six dog‐associated strains. Conclusions: Collectively, our data emphasize the importance of antimicrobial stewardship and sustained biosurveillance beyond human‐ and agriculture‐associated veterinary medicine, using a One‐Health framework that accounts for all transmission points including companion animals. [ABSTRACT FROM AUTHOR]

As of today, bacteriological identification and the molecular approach PCR are considered the gold standards for Salmonella spp. detection. However, these methods are time-consuming and costly due to the requirements for enrichment and nucleic acid extraction. In this study, we evaluated the reliability of a developed colorimetric loop-mediated isothermal amplification (cLAMP) assay targeting the hilA gene, using Phenol Red as an amplification indicator. Given that Phenol Red is pH-dependent, and to develop an extraction-free test, we evaluated chicken meat pretreatment and thermal treatment. First, we assessed the reliability of this test using a pure culture of Salmonella spp. and then in 50 chicken samples pretreated with optimal NaOH concentrations under standardized conditions. Samples representing extreme pH values were artificially contaminated and subjected to DNA extraction and a heat-treatment protocol. Serial dilutions of these products served as templates for LAMP reactions. The assay sensitivity was estimated to be around 3.9 CFU/µL of pure bacterial culture. In contrast, in biological samples, we detected up to 10 CFU/µL using DNA extraction, while heat treatment successfully amplified the initial solution and even some dilutions up to 103 CFU/µL. In conclusion, our cLAMP assay demonstrated good sensitivity and provided clear evidence of its potential for in-field use without relying on prior enrichment steps and DNA extraction. [ABSTRACT FROM AUTHOR]

In this study, we observed the effect of the newly isolated probiotic strain Limosilactobacillus reuteri B1/1 on the relative gene expression of selected cytokines (interleukin-15, transforming growth factor-β4), tight junction proteins (E-cadherin, occludin), biomarker active intestinal stem cells - LGR5 (leucine-rich repeat containing G protein-coupled receptor), markers of mucosal intestinal immunity (mucin-2, immunoglobulin A), as well as the creation of a new biomarker of inflammation in the intestine - calprotectin on an ex vivo model of chicken ileal explant in the prevention of Salmonella Enteritidis PT4 infection. The ability of L. reuteri B1/1 to effectively modulate the mucosal immune response under pretreatment conditions in S. Enteritidis PT4 infection in a chicken ileal explant model was confirmed. In addition, our obtained results point to the fact that the new chicken ileum explant model could be a suitable model to investigate or test the influence of natural substances such as probiotic bacteria in the interaction with the intestine as well as pathogenic microorganisms. In addition, the results of our study may contribute to a deeper understanding of the action of newly isolated probiotic bacteria at the intestinal level using ex vivo models such as chicken ileum explant, which are able to mimic in vivo conditions sufficiently. [ABSTRACT FROM AUTHOR]

The correction notice for the article "Prevalence of Salmonella and Shigella species and their multidrug resistance patterns among pediatric populations in Ethiopia" in BMC Infectious Diseases addresses the incorrect replacement of figures during production. The original article has been corrected, and the corrected figures now accurately represent the data. The authors of the study are listed as Mihret Tilahun, Melaku Ashagrie Belete, Alemu Gedefe, Habtu Debash, Ermiyas Alemayehu, Daniel Gebretsadik Weldehana, Hussein Ebrahim, Ousman Mohammed, Bruktawit Eshetu, Saba Gebremichael Tekele, Zewudu Mulatie, and Agumas Shibabaw. [Extracted from the article]

Salmonella Dublin is a serovar that causes severe infections and cattle. Despite the importance of this agent, research on achieving its elimination from dairy farms is limited, which complicates risk mitigation and control efforts. This study thus aimed to assess the prevalence of S. Dublin on a farm with a history of outbreaks, to understand the dynamics of the infection, characterize the antimicrobial resistance of the isolates, and evaluate their genetic similarity. Multiparous cows in the postpartum phase are nearly five times more likely to shed Salmonella sp. A total of 39 cases of fatal septicemic salmonellosis caused by S. Dublin were confirmed in calves aged 3–5 months. Antimicrobial susceptibility was evaluated in 45 strains of S. Dublin, with 48.9% of the isolates classified as multidrug resistant, including resistance to penicillin (48.9%), tetracyclines (42.2%), and fluoroquinolones (33.3%). Seven multidrug-resistant isolates were selected for genomic sequencing. Among the resistance determinants identified, a mutation in the gyrA gene, present in all sequenced isolates, was notable. Analyses of cgMLST and SNPs revealed that the isolates from healthy animals were closely related to those found in animals with confirmed cases of S. Dublin, confirming that the agent was circulating among healthy animals across various categories. A high similarity was also found between the isolates in this study and strains causing salmonellosis in humans in Brazil, thus reinforcing the zoonotic nature and possible epidemiological link between cattle, and the occurrence of this disease in humans. [ABSTRACT FROM AUTHOR]

Conjugation is a complex phenomenon involving multiple plasmid, bacterial, and environmental factors. Here we describe an IncI1 plasmid encoding multidrug antibiotic resistance to aminoglycosides, sulfonamides, and third-generation cephalosporins. This plasmid is widespread geographically among animal, human, and environmental sectors. We present data on the transmissibility of this plasmid from Salmonella enterica ser. Kentucky into 40 strains of S. enterica (10 strains each from serovars Enteritidis, Heidelberg, Infantis, and Typhimurium). Thirty seven out of 40 strains were able to take up the plasmid. Rates of conjugation were variable between strains ranging from 10−8 to 10−4. Overall, serovars Enteritidis and Typhimurium demonstrated the highest rates of conjugation, followed by Heidelberg, and then Infantis. No relationships were observed between the recipient cell surface and rate of conjugation. Recipient cell numbers correlated positively with conjugation rate and strains with high conjugation rates had marginally but significantly higher growth parameters compared to strains that took up the plasmid at lower frequencies. Environmental conditions known to impact cell growth, such as temperature, nutrient availability, and the presence of antibiotics, had a modulating effect on conjugation. Collectively, these results will further understanding of plasmid transmission dynamics in Salmonella, which is a critical first step towards the development of mitigation strategies. [ABSTRACT FROM AUTHOR]

Background: Salmonella and Shigella are major enteric pathogens that cause diarrhea in children worldwide. They are pathogenic microbes that cause significant diarrheal morbidity and mortality in under five children in resource limited countries. Thus, this systemic review and meta-analysis aimed to investigate the prevalence of Salmonella and Shigella species and their multidrug resistance patterns in pediatric populations in Ethiopia. Methods: The articles were searched extensively in the electronic databases and grey literature using entry terms or phrases. Studies meeting the eligibility criteria were extracted in MS Excel and exported for statistical analysis into STATA version 14 software. The overall pooled prevalence of Salmonella and Shigella species was computed using a random-effects model. Heterogeneity was assessed using the Cochrane Q test and I2 statistics with corresponding p-values. Publication bias was assessed using a funnel plot and Egger's test. In addition, sensitivity analysis was performed to determine the impact of individual studies on the pooled effect size. Result: Of a total of 742 identified studies, 89 studies were eligible for full-text analysis. Of 89 studies, 21 were included for meta-analysis involving 5318 study participants. These eligible studies reported a total of 593 bacterial isolates. The overall pooled prevalence of Salmonella and Shigella among pediatrics in Ethiopia was 10.70% (95% CI: 8.96–12.45), with substantial heterogeneity (I2 = 82.1%, p < 0.001) across the studies. The pooled prevalence of Salmonella and Shigella individually among pediatrics in Ethiopia was 15.43% (95% CI: 10.42–20.72) and 15.83% (95% CI: 11.40–20.40), respectively. Moreover, the overall prevalence of multidrug resistance in Salmonella and Shigella isolates was 81.03% (95% CI: 77.39–84.67) with substantial heterogeneity of I2 of 95%, p < 0.0001 between the pooled prevalence of the two species. Conclusion: The pooled prevalence of Salmonella and Shigella and their multidrug resistance were alarmingly high in pediatric. The initial empirical treatment of pediatrics patients remains challenging and results high prevalence of antimicrobial resistance. Thus, appropriate infection prevention and control strategies should be implemented and treatment should be directed based on antimicrobial stewardship protocols. [ABSTRACT FROM AUTHOR]

Background: Salmonella infections represent a major global public health concern due to their widespread zoonotic transmission, antimicrobial resistance, and associated morbidity and mortality. This review aimed to summarize the zoonotic nature of Salmonella, the challenges posed by antimicrobial resistance, the global burden of infections, and the need for effective vaccination strategies to mitigate the rising threat of Salmonella. Methods: A systematic review of literature was conducted using databases such as PubMed, Scopus, Web of Science, and Google Scholar. Relevant studies published in English were identified using keywords including Salmonella, vaccination, antimicrobial resistance, and public health. Articles focusing on epidemiology, vaccine development, and strategies to control Salmonella infections were included, while conference abstracts and non-peer-reviewed studies were excluded. Results: Salmonella infections result in approximately 95 million global cases annually, with an estimated 150,000 deaths. Regional variations were evident, with higher infection rates in low- and middle-income countries due to poor sanitation and food safety standards. Salmonella Enteritidis and S. Typhimurium were the most prevalent serovars associated with human infections. The review highlighted an alarming rise in multidrug-resistant (MDR) Salmonella strains, particularly due to the overuse of antibiotics in humans and livestock. Despite progress in vaccine development, challenges remain in achieving a universal vaccine that targets diverse Salmonella serovars. Live-attenuated, killed, recombinant, subunit, and conjugate vaccines are currently under development, but limitations such as efficacy, cost, and accessibility persist. Conclusions: Salmonella infections continue to impose a significant burden on global health, exacerbated by rising antimicrobial resistance. There is an urgent need for a multifaceted approach, including improved sanitation, prudent antibiotic use, and the development of affordable, broad-spectrum vaccines. Strengthening surveillance systems and promoting collaborative global efforts are essential to effectively control and reduce the burden of Salmonella. [ABSTRACT FROM AUTHOR]

Introduction: Non-typhoidal Salmonella enterica (NTS) are leading bacterial agents of foodborne illnesses and a global concern for human health. While there are over 2,600 different serovars of NTS, epidemiological data suggests that certain serovars are better at causing disease than others, resulting in the majority of reported human illnesses in the United States. To improve food safety, there is a need to rapidly detect these more pathogenic serovars to facilitate their removal from the food supply. Methods: Addressing this need, we conducted a comparative analysis of 23 closed Salmonella genomic sequences of five serotypes. The analysis pinpointed eight genes (sseK2 , sseK3 , gtgA/gogA , avrA , lpfB, SspH2, spvD, and invA) that in combination, identify 7 of the 10 leading Salmonella serovars attributed to human illnesses in the US each year (i.e., Serovars of Concern or SoC). A multiplex PCR assay was developed to detect the presence of these genes, with strains amplifying five or more targets designated Highly Pathogenic Salmonella , or HPS. The utility of the resulting HPS assay for identifying SoC was examined in silico , using BLAST to determine the distribution of gene targets among closed Salmonella genome sequences in GenBank (n = 2,192 representing 148 serotypes) and by assaying 1,303 Salmonella (69 serotypes), isolated from FSIS regulatory samples. Results and discussion: Comparison of serotypes identified by the assay as HPS, with those identified as SoC, produced an Area Under the Curve (AUC) of 92.2% with a specificity of 96% and a positive predictive value of 97.4%, indicating the HPS assay has strong ability to identify SoC. The data presented lay the groundwork for development of rapid commercial assays for the detection of SoC. [ABSTRACT FROM AUTHOR]

The flagellar MS-ring is the initial template for flagellar assembly and houses the flagellar protein export complex. The MS-ring has three parts of different symmetries within the ring structure by assembly of FliF subunits in two different conformations with distinct arrangements of three ring-building motifs, RBM1, RBM2, and RBM3. However, it remains unknown how these symmetries are generated. A combination of cryoEM structure and structure-based mutational analyses demonstrates that the well-conserved DQxGxxL motif in the RBM2-RBM3 hinge loop allows RBM2 to take two different orientations relative to RBM3. Of 34 FliF subunits of the MS-ring in the basal body, 23 RBM2 domains form an inner ring with a central pore that accommodates the flagellar protein export complex, and the remaining 11 RBM2 domains form 11 cog-like structures together with RBM1 domains just outside the inner RBM2-ring. We propose that a dimer of FliF with two different conformations initiates MS-ring assembly. Kinoshita et. al. demonstrate that the flagellar MS-ring, essential for flagellar assembly, forms through FliF subunits adopting two conformations, generating three distinct symmetries. Using cryoEM and mutational analyses, they identified the conserved DQxGxxL motif as key to this process, enabling precise assembly critical for housing the flagellar protein export complex. [ABSTRACT FROM AUTHOR]

Infections caused by human pathogenic bacteria in food sources pose significant and widespread concerns, leading to substantial economic losses and adverse impacts on public health. This review seeks to shed light on the recent literature addressing the prevalence of Salmonella in the food supply chains of North African countries. Additionally, it aims to provide an overview of the available information regarding health-related concerns, such as virulence genes, and the presence of antibiotic resistance in Salmonella. This review highlights a gap in our comprehensive understanding of Salmonella prevalence in the food supply chains of North African nations, with limited molecular characterization efforts to identify its sources. Studies at the molecular level across the region have shown the diversity of Salmonella strains and their virulence profiles, thus, these results show the difficulty of controlling Salmonella infections in the region. In addition, the discussion of antibiotic resistance makes it clear that there is a need for the development of comprehensive strategies to fight the potential threat of antimicrobial resistance in Salmonella strains. Despite common reports on animal-derived foods in this region, this review underscores the persistent challenges that Salmonella may pose to food safety and public health in North African countries. [ABSTRACT FROM AUTHOR]

Agricultural water is a potential source of microbial contamination whereby Escherichia coli, Salmonella, Cryptosporidium, and Cyclospora cayetenensis can enter the food supply. To reduce this risk, effective sanitization of agricultural water may be critical to food safety. As such, it is important to investigate the effects of aqueous peracetic acid (PAA) and chlorine (Cl) on bacteria and protozoa at different treatment times and temperatures in agricultural water with respect to key water characteristics. Multiple concentrations of each sanitizer, ranging from 3 to 200 ppm, were prepared in recently collected agricultural water, the solution was brought to the desired temperature, and the target organisms were added and left for the desired contact time (5 or 10 minutes) when sodium metabisulfite was added to neutralize the sanitizers. Bacterial samples were enumerated on MacConkey or XLT4 agar. Samples with protozoa were added to mammalian cell culture (HCT-8 cells for Cryptosporidium parvum and MDBK cells for Eimeria tenella). After 48 hours, the infected cells were collected, DNA extracted and infectivity assessed by quantitative PCR (qPCR). Low and high concentrations of sanitizer were effective at eliminating bacteria with Cl being significantly (P < 0.05) more effective. The greatest reductions in E. coli and Salmonella (3.48 log and 2.5 log cfu/mL, respectively) were observed after 10 minutes of exposure to 10 ppm Cl. Concentrations of sanitizer 50 ppm and lower resulted in insignificant (P > 0.05) reductions in parasite infectivity of less than 1 log for both organisms. A 200 ppm PAA treatment reduced infectious oocyst populations by 3.8 log for C. parvum and 2.6 log for E. tenella, with Cl being significantly (P < 0.05) less effective against these organisms. [ABSTRACT FROM AUTHOR]

Background Salmonella Infantis is an emerging multidrug-resistant pathogen worldwide due to the acquisition of a megaplasmid, plasmid of emerging Salmonella Infantis (pESI). Reported initially in poultry, the distribution of pESI-harboring S. Infantis in other food types, including seafood, is unknown. Objective This study aimed to develop and optimize a PCR assay for detecting the pESI in Salmonella and non- Salmonella Enterobacterales. Methods A duplex PCR targeting the hilA gene and a pESI-associated gene of S. Infantis was designed, and the PCR conditions were optimized. The specificity and sensitivity of the assay were established using 119 Salmonella serovars and 51 non- Salmonella bacterial strains. Results All Salmonella isolates yielded hilA PCR product, while only pESI S. Infantis was positive for both hilA and pESI genes. No amplification product was obtained with the DNA of 51 non- Salmonella bacterial strains. The detection limit of the duplex PCR was 104 CFU/mL of pure culture of pESI S. Infantis. The sensitivity of detection in artificially spiked shrimp meat was 1 CFU/g after 6 h of enrichment in lactose broth, followed by 12 h of selective enrichment in the Rappaport-Vassiliadis medium. Conclusion The duplex assay will help screen seafood for Salmonella in general and pESI S. Infantis in particular. Given its high sensitivity, the PCR will be a valuable tool for seafood quality assurance. This approach decreases the typical 3–6 day identification time of Salmonella to less than 24 h. Highlights S. Infantis carrying the highly transmissible megaplasmid (pESI) is a significant food safety concern. Given its rapid geographical spread and high antimicrobial-resistant traits, it is necessary to have a molecular tool that detects pESI-harboring Salmonella. This study successfully developed a duplex PCR assay that simultaneously detects Salmonella enterica and pESI S. Infantis. This molecular tool will help understand the distribution, sources, and spread of the multidrug-resistance (MDR) plasmid in the food environment. [ABSTRACT FROM AUTHOR]

Foodborne pathogens such as Salmonella spp.and Campylobacter spp. pose significant threats to the safety of broiler meat worldwide. However, data on their prevalence in retail chicken meat in Saudi Arabia are scarce. This context mainly concerns the vast poultry market in Saudi Arabia, which may double by 2030. The overall objective of this study was to determine the prevalence and antibiotic resistance of Salmonella spp. and Campylobacter spp. in retail chickens from small, medium-sized, and large production companies in Saudi Arabia. Of the 212 chicken samples tested, Salmonella was detected in 9.3% of samples, all identified as Salmonella enterica serovar Enteritidis. Campylobacter was more prevalent, found in 35.8% of samples, with Campylobacter jejuni accounting for 26.4% and Campylobacter coli for 9.3%. Pathogen prevalence was higher in small-scale than in medium-sized and large producers. Salmonella Enteritidis isolates were resistant to nalidixic acid (90%), amoxicillin-clavulanic acid, and tetracycline (70%). Most Campylobacter coli isolates (90%) exhibited resistance to erythromycin, clindamycin, and gentamicin, followed by tetracycline (80%). Campylobacter jejuni isolates showed high resistance to erythromycin, clindamycin, tetracycline, azithromycin, and nalidixic acid (75–92%). Multidrug resistance (MDR) was observed in all Campylobacter jejuni isolates, 90% of Campylobacter coli isolates, and 70% of Salmonella isolates. These findings underscore the urgent need for adherence to food safety guidelines, particularly in small-scale poultry farms. The pervasive presence of MDR Salmonella spp. and Campylobacter spp. in broiler meat calls for enhanced surveillance, stricter enforcement of food safety practices, and public health initiatives to mitigate the risk of foodborne diseases in Saudi Arabia. [ABSTRACT FROM AUTHOR]

This study characterized the genome of three Salmonella enterica serovar Heidelberg (S. Heidelberg) strains with different antimicrobial resistance (AMR) profile that were inoculated as a cocktail into fresh pine wood shavings (PWS). The strains were isolated from feces (SH-AAFC), carcass (SH-ARS), and thigh (SH-FSIS) of broiler chicken. SH-AAFC harbored an antimicrobial resistant gene (ARG) blaCMY-2 on an IncI1 plasmid while SH-FSIS harbored multiple ARGs (floR, cmlA1, tet(A), blaTEM-1B, ant(2″)-Ia, aph(6)-Id, aph(3″)-Ib, and sul2) on an IncC plasmid. SH-ARS was pan-susceptible. The die-off of Salmonella was determined at days 0, 1, 7, 14, and 21. Antibiotic susceptibility tests and whole genome sequencing were performed on 77 isolates. At 21 days post-inoculation, Salmonella abundance decreased by 4.4 Log10 CFU/g with the water activity of PWS being correlated with Salmonella survival. SH-AAFC clonal populations survived longer in PWS than SH-FSIS and SH-ARS populations. SH-AAFC clones persisting in litter carried higher copy number of Col plasmids than their ancestors, while some SH-ARS clones acquired a lysogenic bacteriophage from SH-FSIS populations. These results suggest that mobile genetic determinants such as plasmids (which could carry ARGs) and bacteriophage plays roles in the persistence of S. Heidelberg in the PWS used as broiler litter. Highlights: S. Heidelberg survived up to 21 days in PWS which is often used as broiler bedding. S. Heidelberg abundance and survival was correlated with the water activity of PWS. S. Heidelberg strains that carried higher copy numbers of small Col plasmids were the dominant strains isolated from PWS at later time points. S. Heidelberg strains harboring transmissible plasmid carrying AmpC-like beta-lactamase gene persisted longer in PWS without antibiotic pressures for AMR. [ABSTRACT FROM AUTHOR]

These case reports describe two neonates, born at term, diagnosed with bacterial meningitis and septicemia caused by uncommon organisms. The clinical presentation, diagnostic reasoning, national guidelines, hospital course, and follow-up are discussed. Meningitis is among the differential diagnoses when there is a concern for neonatal sepsis. Concern for sepsis can arise from a variety of antepartum, intrapartum, and postpartum risk factors and present with a variety of symptoms. Neonatal sepsis is a significant cause of mortality, with 750,000 infant deaths annually. Effective treatment of neonatal sepsis requires timely diagnosis and tailored antimicrobial therapy that targets the causative pathogens. [ABSTRACT FROM AUTHOR]

Milk and its derivatives serve as significant reservoirs of Salmonella, particularly for individuals who favor the consumption of untreated milk. The prevalence of Salmonella infections is influenced by various factors, including unsatisfactory hygiene practices on farms, the conduct of food handlers, and the consumption of raw milk and milk-based products. Salmonella is a leading cause of salmonellosis, a prominent global foodborne illness. This study aimed to investigate the presence of Salmonella in marketable milk and some dairy products in New Valley Governorate, Egypt. A total of 150 random samples of commercially available milk and some milk products, such as soft cheeses (Kareish, Domiati), and ice cream (30 samples for each category), were collected from diverse locations within New Valley Governorate. The prevalence rates were found to be 1.6% for marketable milk, on the other hand, Salmonella species couldn't be detected in Kareish cheese, Domiati cheese, and ice cream samples. In conclusion, the detection of Salmonella in milk suggests that the examined samples exhibited suboptimal quality, indicative of unhygienic practices throughout the entire milking, processing, storage, and distribution processes. [ABSTRACT FROM AUTHOR]

Salmonellosis is one of the most important bacterial diseases that results in many public health risks. This study aims to investigate the prevalence of non-typhoidal-Salmonella (NTS) in pets and humans in New Valley Governorate, Egypt, and study their most important risk factors to help in proposing plans to prevent and control salmonellosis. A total number of 920 samples were collected from pets' feces and human's stool. The bacteriological examination of collected samples revealed that the prevalence of NTS in the New Valley Governorate was 1.7% in humans and 1.6 % in pets (0.9% in cats, and 2.2% in dogs). The locality, season, health status, sex, and age can significantly affect the prevalence of salmonellosis in pets and humans. All Salmonella isolates from dogs, cats, and humans were only obtained in the cold season and from cats, dogs, and humans with diarrhea and gastrointestinal manifestation and no Salmonella could be isolated from apparently healthy ones. Salmonella was recovered from male dogs (3.5%) more than bitches (1.1%), also male cats (1.25%) were more than female cats (0%). In addition, Salmonella isolates from human males (4.4%) were more than females (0.4%). The highest prevalence of salmonellosis was detected in the young age group, < 6 months, of dogs (2.5%) and cats (1.4%). On the other hand, the highest prevalence of human salmonellosis was found in group D (> 40: 60 years) followed by group A (<6 years) by 7.5% &1.7%, respectively. The prevalence of salmonellosis was higher in individuals of close contact with their pets (1.7%) than those of non-contacts (1.5%). Pet sanitary practices and personal hygiene are very important measures for Salmonella prevention. The routine examination of pets against salmonellosis is recommended. [ABSTRACT FROM AUTHOR]

Lactic acid bacteria (LAB), known for their health benefits, exhibit antimicrobial and antibiofilm properties. This study investigated the cell-free supernatant (CFS) of Lactobacillus spp., particularly L. plantarum KR3, against the common foodborne pathogens S. aureus, E. coli and Salmonella spp. Lactobacillus strains were isolated from cheese, pickles and yoghurt. They were then identified by morphological, physiological and biochemical characteristics and confirmed by 16S rRNA gene sequencing. Culture supernatants from seven lactobacilli isolates showed varying inhibitory activities. Notably, L. plantarum KR3 and L. pentosus had the highest bacteriocin gene counts. L. plantarum KR3 CFS demonstrated significant antibacterial activity, with inhibition zones of 20 ± 0.34 mm for S. aureus, 23 ± 1.64 mm for E. coli, and 17.1 ± 1.70 mm for Salmonella spp. The CFS also exhibited substantial antibiofilm activity, with 59.12 ± 0.03% against S. aureus, 83.50 ± 0.01% against E. coli, and 60. ± 0.04% against Salmonella spp., which were enhanced at the minimum inhibitory concentration (MIC). These results highlighted the potential of L. plantarum KR3 in antimicrobial applications, however, further research is needed to evaluate its viability and functional properties for probiotic use. Additionally, the CFS demonstrated exceptional thermal stability, reinforcing its promise as an antimicrobial agent. [ABSTRACT FROM AUTHOR]

Simple Summary: This study aimed to evaluate the impact of two types of plastic flooring—one with and one without nanotechnological antimicrobial additives—used as a complete or partial replacement for wood shavings on various aspects of broiler chicken production. The investigation focused on the performance, yield, meat quality, and litter microbiology in broilers raised until 42 days of age. A completely randomized design was employed using Ross 408® male broiler chicks, which were distributed in five treatments that included wood shavings, plastic flooring, and combinations of both. This study included organ biometrics, the macroscopic evaluation of Eimeria lesions, microbiological analysis, performance indices, and meat quality parameters. The findings indicated that plastic flooring presented several challenges, such as a greater incidence of coccidiosis-related intestinal lesions, as well as negative effects on performance, body weight, and carcass yield, when compared to wood shavings. This study evaluated the effects of two types of plastic flooring—one with and one without nanotechnological antimicrobial additives—used as complete or partial replacements for wood shavings on broiler chicken performance, yield, meat quality, and litter microbiology over 42 days. A total of 1500 Ross 408® male broiler chicks were randomly assigned to five treatment groups: wood shavings (WS), plastic flooring (PF), a 50/50 mix of plastic flooring and wood shavings (PF + WS), plastic flooring with antimicrobial additives (PFA), and a 50/50 mix of antimicrobial plastic flooring and wood shavings (PFA + WS). This study evaluated organ biometrics (liver, heart, spleen, and gizzard), the severity of Eimeria lesions, microbiological profiles, performance indices, and meat quality. The results indicated that plastic flooring, particularly when used alone, presented challenges such as increased intestinal lesions related to coccidiosis and a higher prevalence of Salmonella. Moreover, broilers raised on plastic flooring presented worse feed conversion and lower body weights and carcass yields than those raised on wood shavings. The meat quality was also negatively affected, with plastic flooring leading to less favorable fillet characteristics. Overall, the use of plastic flooring reduced the performance and health parameters of broiler chickens. [ABSTRACT FROM AUTHOR]

Non-typhoidal salmonellosis is a foodborne disease caused by Salmonella spp. Most outbreaks of this disease are commonly associated with consuming contaminated meat products, hence the importance of monitoring ready-to-eat artisanal pork sausages for the presence of these bacteria. A total of 494 samples of grilled and smoked barbecue artisanal pork sausages were collected at food outlets from 12 municipalities of the Department of Quindío, Colombia, between 2017 and 2022. Salmonella spp. was identified using VIDAS® Easy SLM and confirmed through API® 20 E. Salmonella spp. was detected in 260 samples (52.6%), and the highest rates of contamination were found in Armenia (65.7%), Salento (65.2%), Circasia (57.7%), and Calarcá (56.4%). The highest proportion of these samples positive for Salmonella spp. was ready-to-eat smoked barbecue artisanal sausages (68.8%) sold by street vendors (58.4%) from 12 municipalities of the Department of Quindío. A significant association was observed between the municipality and contamination of samples with Salmonella spp. However, no link was found between the sampling year and the presence of the bacteria. This is the first study aimed at monitoring the presence of Salmonella spp. in artisanal pork sausages sold in the municipalities of the Department of Quindío over a 6-year period, and findings revealed very high percentages of contamination. Although Colombian legislation establishes sanitary and safety requirements for meat production, the presence of Salmonella spp. in artisanal sausages remains a persistent public health threat in developing countries. [ABSTRACT FROM AUTHOR]

Historically, there has been a concern for the detection and enumeration of microorganisms in foods, and numerous methods have been developed to determine their microbiological conditions. The present study aimed to compare the numbers of microbes recovered with three sampling methods: drip, excision, and swabbing in vacuum-packed beef. The sampling methods were evaluated in terms of the viable numbers of Enterobacteriaceae, lactic acid bacteria (LAB), Brochrothrix thermosphacta, Salmonella spp., and yeasts and moulds (Y&M). The numbers of B. thermosphacta, Salmonella spp., Enterobacteriaceae, LAB, and M&Y recovered with the drip method were significantly higher (p < 0.05) than those from the other two methods. Regarding excision and swabbing, the recovery of B. thermosphacta and Enterobacteriaceae was higher (p < 0.05) with the excision method than swabbing, while there were no statistical differences (p > 0.05) between both methods for Salmonella spp., LAB, and Y&M. In conclusion, the drip method can recover up to two logarithms more than the other techniques in vacuum-packed meat; hence, it should be considered when designing and implementing sampling systems for the meat industry. [ABSTRACT FROM AUTHOR]

This paper examines the responses of chicken producers to public disclosure of quality information (or categorization) regarding Salmonella in chicken carcasses. Producers exert effort to attain better categorization and shirk when failing to meet the thresholds required for better categorization. Public disclosure reduces this shirking effect. However, some producers shirk even under public disclosure when the threshold for disclosure is too stringent. The results suggest that the most effective quality disclosure policies would either disclose continuous (noncategorical) information or impose fines or other sanctions on producers attaining the poorest quality. [ABSTRACT FROM AUTHOR]

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This study investigated the survival and growth of Salmonella in onion extracts and bulbs. The inhibition or retardation of Salmonella growth by extracts of red, white, and yellow onions was tested against the onion germplasm and exposure to different light spectra during curing. Separately, survival of Salmonella Newport was tested on red, white, and yellow onion bulbs on the external and internal onion layers with a syringe and needle. Onions exposed to blue, red, and white LED light during curing produced extracts with variable antimicrobial effects (p < 0.05), with those exposed to blue light showing the strongest inhibitory effect on red and white onions only. In survival studies, Salmonella inoculated on the outer scale was reduced by 1.2, >2.7, and >2.4 logs on red, white, and yellow onions, respectively, within 3 days, whereas it grew by 2.4, 2.6, and 2.8 logs inside red, white, and yellow onion bulbs, respectively, over 18 days. In separate trials, the outer layer again did not support the survival of Salmonella Newport. The aw increased significantly from 0.51 to 0.58 in the outer scales and 0.96 to 0.98 for the fourth inner scales. Despite being rich in antimicrobial polyphenols, tissue integrity and water content may still promote Salmonella growth in onions. [ABSTRACT FROM AUTHOR]

Vaccines that cross-protect across serovars of Salmonella enterica (Salmonella) would be a beneficial intervention against emerging and persistent Salmonella isolates of concern for the turkey industry. The 2017–2019 foodborne outbreak of Salmonella enterica serovar Reading (S. Reading) revealed the need for effective control of this serovar in turkey production. This study evaluated two live-attenuated Salmonella vaccines, an internally developed cross-protective vaccine and a commercially available vaccine, against an outbreak-associated strain of S. Reading in turkeys. At 1 day and 3 weeks of age, male turkey poults were either mock-vaccinated with phosphate buffered saline (PBS) or given one of the vaccines by oral gavage (primary and booster) or aerosol spray (primary) then drinking water (booster). At 7 weeks of age, poults were challenged with 109 colony forming units (CFU) of S. Reading; a mock-vaccinated group was mock-challenged with PBS. Colonization of the cecal contents and cecal tonsil was 1.5–3 log10 CFU/g lower in vaccinated birds than mock-vaccinated birds at 7 and/or 14 days post-inoculation (DPI). Salmonella dissemination to the spleen was significantly reduced by both vaccines. Gene expression of intestinal transporters (such as SCNN1B and SLC10A2) and tight junction proteins was significantly decreased in the turkey cecal tonsil transcriptome at 2 DPI with S. Reading. Vaccination with either vaccine mitigated most cecal tonsil gene expression responses to S. Reading challenge. Therefore, both the internally developed vaccine and commercial vaccine were cross-protective against colonization and dissemination, and both were able to limit transcriptional changes from challenge in intestinal health-related genes in the cecal tonsil, thereby providing vaccination efficacy and impact data against S. Reading in turkeys. [ABSTRACT FROM AUTHOR]

Immunotherapy has revolutionized cancer treatment, yet its effectiveness is limited by immunosuppressive tumor microenvironment (TME). To overcome this challenge, innovative strategies to effectively modulate the TME are urgently needed. Over the past decades, bacteria-mediated cancer immunotherapy has recaptured increasing attention, driven by advances in synthetic biology, genetic engineering and our knowledge of host–pathogen interactions. Among various bacterial species, Salmonella has emerged as a leading candidate with significant therapeutic potential due to its broad-spectrum anti-tumor activity, tumor-targeting ability, immunomodulatory effects, oncolytic properties, genetic programmability, and engineering flexibility. These characteristics enable Salmonella to reshape the immunosuppressive TME, thereby enhancing anti-tumor efficacy. This review elaborates the regulatory effects of Salmonella on key components of the TME, the versatile engineering strategies for optimizing Salmonella's ability to modulate the TME, and recent advancements in combination cancer therapies. We also summarize current clinical applications and discuss challenges of developing safer and more effective Salmonella-based cancer immunotherapy. [ABSTRACT FROM AUTHOR]

Type VI Secretion Systems (T6SS), widely distributed in Gram-negative bacteria, contribute to interbacterial competition and pathogenesis through the translocation of effector proteins to target cells. Salmonella harbor 5 pathogenicity islands encoding T6SS (SPI-6, SPI-19, SPI-20, SPI-21 and SPI-22), in which a limited number of effector proteins have been identified. Previous analyses by our group focused on the identification of candidate T6SS effectors and cognate immunity proteins in Salmonella genomes deposited in public databases. In this study, the analysis was centered on Salmonella isolates obtained from environmental sources in Chile. To this end, bioinformatics and comparative genomics analyses were performed using 695 genomes of Salmonella isolates representing 44 serotypes obtained from surface water and animal sources in Chile to identify new T6SS effector proteins. First, T6SS gene clusters were identified using the SecreT6 server. This analysis revealed that most isolates carry the SPI-6 T6SS gene cluster, whereas the SPI-19 and SPI-21 T6SS gene clusters were detected in isolates from a limited number of serotypes. In contrast, the SPI-20 and SPI-22 T6SS gene clusters were not detected. Subsequently, each ORF in the T6SS gene clusters identified was analyzed using bioinformatics tools for effector prediction, identification of immunity proteins and functional biochemical prediction. This analysis detected 20 of the 37 T6SS effector proteins previously reported in Salmonella. In addition, 4 new effector proteins with potential antibacterial activity were identified in SPI-6: 2 Rhs effectors with potential DNase activity (PAAR-RhsA-NucA_B and PAAR-RhsA-GH-E) and 2 effectors with potential RNase activity (PAAR-RhsA-CdiA and RhsA-CdiA). Interestingly, the repertoire of SPI-6 T6SS effectors varies among isolates of the same serotype. In SPI-19, no new effector protein was detected. Of note, some Rhs effectors of SPI-19 and SPI-6 present C-terminal ends with unknown function. The presence of cognate immunity proteins carrying domains present in bona fide immunity proteins suggests that these effectors have antibacterial activity. Finally, two new effectors were identified in SPI-21: one with potential peptidoglycan hydrolase activity and another with potential membrane pore-forming activity. Altogether, our work broadens the repertoire of Salmonella T6SS effector proteins and provides evidence that SPI-6, SPI-19 and SPI-21 T6SS gene clusters harbor a vast array of antibacterial effectors. [ABSTRACT FROM AUTHOR]

Introduction: Typhoid fever is an infectious disease primarily caused by Salmonella enterica sv. Typhi (S. Typhi), a bacterium that causes as many as 20 million infections and 600,000 deaths annually. Asymptomatic chronic carriers of S. Typhi play a major role in the transmission of typhoid fever, as they intermittently shed the bacteria and can unknowingly infect humans in close proximity. An estimated 90% of chronic carriers have gallstones; biofilm formation on gallstones is a primary factor in the establishment and maintenance of gallbladder carriage. CsgD is a central biofilm regulator in Salmonella , but the S. Typhi csgD gene has a mutation that introduces an early stop codon, resulting in a protein truncated by 8 amino acids at the C-terminus. In this study, we investigate the role of role of CsgD in S. Typhi. Methods: We introduced a fully functional copy of the csgD gene from S. Typhimurium into S. Typhi under both a native and a constitutive promoter and tested for red, dry, and rough (Rdar) colony morphology, curli fimbriae, cellulose, and biofilm formation. Results and discussion: We demonstrate that although CsgD-regulated curli and cellulose production were partially restored, the introduction of the S. Typhimurium csgD did not induce the Rdar colony morphology. Interestingly, we show that CsgD does not have a significant role in S. Typhi biofilm formation, as biofilm-forming capacities depend more on the isolate than the CsgD regulator. This data suggests the presence of an alternative biofilm regulatory process in this human-restricted pathogen. [ABSTRACT FROM AUTHOR]

Objective: Salmonella is an important zoonotic foodborne pathogen which is recognized as a major public health concern worldwide. Salmonella contamination are highly prevalent in dog treats and raw meat-based dog food (RMBDs). And dog treats and raw meat-based dog food are often implicated as main sources of human infection. Many epidemiological studies have focused on the characteristics of Salmonella in many countries. But there are no such reports in Japan. This study was conducted to investigate the genetic characteristics of Salmonella using multi-locus sequence typing (MLST). Results: Fourteen Salmonella isolates were assigned to 8 sequence types: ST19, ST26, ST32, ST34, ST241, ST469, ST864 and ST1861. The most common types were ST32 and ST34 (21%, n = 3). The second most common types were ST26 and ST469 (14%, n = 2). [ABSTRACT FROM AUTHOR]

Objective: The foodborne pathogen Salmonella enterica serovar Typhimurium causes self-limiting gastroenteritis in humans and is difficult to eliminate due to its ability to adhere to surfaces and form biofilms that exhibit high resistance to antimicrobial agents. To explore alternative strategies for biofilm treatment, it is essential to investigate novel agents that inhibit Salmonella biofilms. Method: In this study, we investigated the minimum biofilm inhibitory concentrations (MBICs) and minimum biofilm eradication concentrations (MBECs) of nafcillin and diosmin, both previously identified as Lon protease inhibitors, against biofilms formed by S. Typhimurium. Furthermore, we examined the expression of genes associated with the type II toxin-antitoxin system to enhance our understanding of the impact of these inhibitors. Results: The findings indicated a strong antibiofilm effect of nafcillin, with MBIC and MBEC values of 8 µg/mL and 32 µg/mL, respectively. These results were confirmed by field emission scanning electron microscopy (FE-SEM), which showed that biofilm formation was reduced in the presence of nafcillin. Additionally, it revealed morphological changes in the bacteria within the nafcillin-treated biofilms. Furthermore, gene expression analyses demonstrated a significant reduction in the expression of type II TA system genes following treatment with nafcillin and diosmin. Conclusion: This study highlights the effectiveness of nafcillin in disrupting the biofilms of S. Typhimurium. These results suggest promising avenues for the development of novel therapeutic strategies targeting biofilms associated with S. Typhimurium. [ABSTRACT FROM AUTHOR]

Introduction: Salmonella spp. is the second most common bacteria associated with foodborne gastrointestinal outbreaks in humans, with the highest contamination levels in meat, especially poultry. Salmonella enterica subsp. enterica serovar Infantis is the primary serovar isolated from broilers, without causing any symptomatic disease. Conversely, certain human strains can result in symptomatic illness (fever, headache, and diarrhoea). Therefore, reducing S. Infantis colonization in broilers is important before slaughter, to prevent this pathogen carryover along the food chain. Methods: Here, we report the characterization of two S. Infantis virulent phages, isolated from broiler feces. Isolates were phenotypically and genetically characterized. Results and discussion: Phages (ɸ) SaI_NFG_5581 and SaI_NFG_5577 were characterized as strictly lytic versus S. Infantis but with different bacteriolytic activities and genetic features. They both belong to the Caudoviricetes class, but ɸSaI_NFG_5581 (genome length 112,970 bp) belongs to the Demerecviridae family while ɸSaI_NFG_5577 (genome length 42,481 bp) to the Guernseyvirinae family. Genomic analysis excluded the presence of lysogeny, toxin, or antimicrobial resistance genes, and for those reasons, the two phages could be considered safe. Phages are stable under a broad range of pH (4-10) and temperature (4°C-50°C) conditions. In vitro , both ɸSaI_NFG_5581 and ɸSaI_NFG_5577 were able to lower Salmonella counts of about 2.2 LOG/mL and 3.4 LOG CFU/mL respectively, at MOI 0.1 after 2 h of treatment. After 24 h, Salmonella counts treated with both phages remained lower than the control (non-phage-treated Salmonella). These newly isolated phages have promising features, which could be exploited and further studied for potential in vivo application. [ABSTRACT FROM AUTHOR]

Recent listeriosis and salmonellosis outbreaks in the U.S. have been associated with consumption of specialty mushrooms, including enoki and wood ear. These mushrooms are commonly consumed in Asian dishes such as ramen noodle soup and are often used as raw garnishes. No current guidelines exist for the serving temperature of ramen broth in restaurants for safety. The objective of this study was to evaluate the inactivation of both Listeria monocytogenes and Salmonella enterica on enoki and wood ear mushrooms based on the ramen broth temperature. Fresh mushrooms were chopped into pieces, inoculated with four-strain cocktails of L. monocytogenes or S. enterica , dried at ambient conditions for 30 min, then placed into bowls. Ramen broth (i.e., pork bone broth, Tonkotsu) at initial temperatures of 60, 70, 80, 90, or 100°C was poured over the mushrooms, submerging them. The bowls were held at ambient conditions while the broth temperatures were monitored, and mushrooms were sampled at intervals up to 60 min. From the broth temperature profiles and the pathogen log reductions of each mushroom type, the non-isothermal log-linear model was used to obtain maximum inactivation rates. The maximum pathogen inactivation on both mushroom types occurred within the first 5 min, regardless of the initial broth temperature. Broth temperatures of 60 and 70°C resulted in reductions of only 1–3 log CFU/g (inactivation rates of 0.33–4.72 log CFU/g/min), while reductions of 4–5 log CFU/g (inactivation rates of 8.74–17.21 log CFU/g/min) were observed with 80°C broth. The use of 90 and 100°C broth resulted in higher reductions of >5 log CFU/g (inactivation rates of 8.56–28.08 log CFU/g/min). In all cases, surviving populations, often >2.4 log CFU/g, were observed after 60 min. The results from this study can assist in the development of guidelines on the safe serving temperature of ramen soup at restaurants. [ABSTRACT FROM AUTHOR]

To investigate fosfomycin resistance rates in cattle across Japan, we carried out susceptibility tests. To identify the genes contributing to fosfomycin resistance, we performed whole-genome sequencing on the fosfomycin-resistant strains. Escherichia coli were sampled from healthy cattle (n = 292, combined total from 2017, 2020, 2021, and 2022) and diseased cattle (n = 73, from 2021 to 2022). Salmonella spp. were obtained from diseased cattle (n = 74 from 2021 to 2022). These samples originated from different and non-duplicated farms. The MICs to fosfomycin were measured using an agar dilution method with a breakpoint of 256 μg/mL. We conducted whole-genome sequencing with a MiSeq, followed by in silico analysis of the acquired draft genomes. The resistance rates were 0.3% (95% CI [0–1.9%]), 6.8% (95% CI [2.3–15.3%]), and 1.4% (95% CI [0–7.3%]). The FosA3 gene was detected in five out of six fosfomycin-resistant E. coli strains and one Salmonella spp. strain. The fosfomycin-resistant Salmonella spp. strain also has a fosA7 gene. One E. coli strain showed resistance to fosfomycin without having the fosA3 gene, and with the mutations of glpT, uhpT, uhpT and ptsI, and with the existence of efflux pumps. The nationwide scale of resistance rates to fosfomycin in E. coli isolated from healthy and diseased cattle and that of Salmonella spp. from diseased cattle were revealed for the first time, and the resistance rates were low. In addition, genes linked to the mechanism of fosfomycin resistance were identified. [ABSTRACT FROM AUTHOR]

Simple Summary: As a major economic pillar in Tibet, the yak breeding industry is an important source of income and livelihood for local farmers and herdsmen. Salmonella, one of the most important foodborne pathogens globally, has seriously threatened the healthy development of this industry for many years, causing huge economic losses for local herdsmen and related industries. Furthermore, there are many serotypes of Salmonella that can infect different hosts, causing varying degrees of damage. The aim of this study was to investigate the prevalence of Salmonella in yak farms in the Qinghai–Tibet Plateau area. A total of 223 strains of Salmonella were isolated from 1222 fecal samples from yaks from Tibet and Qinghai, with an overall isolation rate of 18.25% (223/1222). These 223 Salmonella isolates were serotyped, and their antimicrobial susceptibility, resistance genes, and virulence genes were investigated. Furthermore, MLST (Multi-Locus Sequence Typing) was applied to the isolates. The results showed that the carriage of Salmonella in Tibetan yaks is quite serious in the Qinghai–Tibet Plateau area, with Enteritidis Salmonella (17.94%) and Typhimurium Salmonella (13.90%) representing the predominant serotypes. Given that the Salmonella isolates also showed resistance to antimicrobial drugs, continuous monitoring of Salmonella infections and resistance in the Qinghai–Tibet Plateau area is needed to avoid the potential risk of foodborne disease transmission. Salmonella is an important foodborne pathogen that can cause a range of illnesses in humans; it has also been a key focus for monitoring in the field of public health, including gastroenteritis, sepsis, and arthritis, and can also cause a decline in egg production in poultry and diarrhea and abortion in livestock, leading to death in severe cases, resulting in huge economic losses. This study aimed to investigate the isolation rate, antimicrobial resistance, serotypes, and genetic diversity of Salmonella isolated from yak feces in various regions on the Qinghai–Tibet Plateau. A total of 1222 samples of yak dung were collected from major cities in the Qinghai–Tibet Plateau area, and the sensitivity of the isolated bacteria to 10 major classes of antibiotics was determined using the K-B paper disk diffusion method for drug susceptibility. Meanwhile, the serotypes of the isolated bacteria were analyzed using the plate agglutination test for serum antigens, and their carriage of drug resistance and virulence genes was determined using PCR and gel electrophoresis experiments. The isolated bacteria were also classified using MLST (Multi-Locus Sequence Typing). The overall isolation rate for Salmonella was 18.25% (223/1222), and the results of the antibiotic susceptibility tests showed that 98.65% (220/223) of the isolated bacteria were resistant to multiple antibiotics. In the 223 isolates of Salmonella, eight classes of 20 different resistance genes, 30 serotypes, and 15 different types of virulence genes were detected. The MLST analysis identified 45 distinct sequence types (STs), including five clonal complexes, of which ST34, ST11, and ST19 were the most common. These findings contribute valuable information about strain resources, genetic profiles, and typing data for Salmonella in the Qinghai–Tibet Plateau area, facilitating improved bacterial surveillance, identification, and control in yak populations. They also provide certain data supplements for animal Salmonella infections globally, filling research gaps. [ABSTRACT FROM AUTHOR]

Salmonella spp. is one of the most important foodborne pathogens worldwide. Given the fact that poultry and poultry products are the main source of human infection, Salmonella control in these farms is of utmost importance. To better control this pathogen in farms, boot swabs are used to sample farm environments but the analysis of these swabs is mainly based on culture-dependent methods. In the present study, a novel loop-mediated isothermal amplification (LAMP) method was developed for the rapid screening of Salmonella spp. in boot swab samples from broiler flock environments. Four different DNA extraction protocols were evaluated in depth, including a simple thermal lysis, a chelex-based protocol and two thermal lysis protocols followed by the purification of magnetic beads made of silica ("glass milk") in order to determine the most suitable alternative for potential on-site, farm analyses. The methodology evaluation included a blind interlaboratory assay and as a proof-of-concept, a naked-eye colorimetric assay was also included. Following the final methodology, it was possible to reach an LoD50 of 1.8 CFU/25 g of the samples, with a high relative sensitivity (95.7%), specificity (100%) and accuracy (96.6%) along with Cohen's kappa of concordance with respect to the ISO standard 6579-1:2017 of 0.9, with an RLOD of 1.3. In addition to this, due to the relevance of certain serotypes with the genus Salmonella spp., a serotype LAMP panel for the specific identification of S. Typhimurium, S. Enteritidis, S. Infantis, S. Hadar and S. Virchow was also developed. Even though some degree of cross-reactivity among the primers developed was observed, all the serotypes could be accurately identified based on their melt curve analysis profile. Taken together, in the present study, a rapid Salmonella spp. screening method, suitable for farm applications, was developed, along with a serotyping panel that could be used in a laboratory setup for the identification of the most relevant serotypes of the genus, taking advantage of real-time amplification followed by melt curve analysis. [ABSTRACT FROM AUTHOR]

Translation terminates at UAG (amber), UGA (opal), and UAA (ochre) stop codons. In nature, readthrough of stop codons can be substantially enhanced by suppressor tRNAs. Stop‐codon suppression also provides powerful tools in synthetic biology and disease treatment. How stop‐codon suppression affects bacterial pathogenesis is poorly understood. Here, we show that suppression of UAG codons, but not UGA or UAA codons, attenuates expression of Salmonella Pathogenicity Island 1 (SPI‐1) genes, which are required for virulence. Consistently, amber suppression abolishes Salmonella infection of macrophages. Systematic genetic and biochemical analyses further show that amber suppression decreases the activity, but not the level, of the master SPI‐1 regulator HilD. Our work thus demonstrates an unexpected selectivity of stop codons in regulating Salmonella virulence. [ABSTRACT FROM AUTHOR]

Salmonella-related foodborne infections are commonly caused by the serovars of S. Typhimurium, which can be detected using antibody-based immunoassays. The monovalent variable domain of the camelid heavy chain antibody (VHH) performs excellently in constructing multivalent VHH variants, which generally exhibit higher affinities with antigens and consequently enhance the assay sensitivity. In this study, the divalent variants of VHHs (diVHHs) targeting S. Typhimurium were generated by encoding the monovalent VHH genes assembled in tandem with a flexible linker peptide (G4S)2. Soluble diVHHs were produced in a prokaryotic expression system and purified with a yield of 4.22 mg/L. Benefiting from their stability and antigen-binding abilities towards tested Salmonella serovars, diVHH-based immunoassays were developed. The diVHH-based sandwich immunoassay, using diVHH as capture antibody, exhibited a detection limit of 1.04×102 CFU/mL and enabled as low as 10 CFU/mL S. Typhimurium to be detected after 6 h of enrichment in lettuce. Furthermore, this assay can be applied to spiked lettuce, chicken, and pork samples, showing acceptable recoveries ranging from 83 to 106%. This study presented feasible strategies for VHH multivalence and established a superior sensitivity VHH-based immunoassay for monitoring and analyzing Salmonella contamination in food. [ABSTRACT FROM AUTHOR]

Most bacteria are polylysogens that carry multiple prophages integrated into the chromosome. These prophages confer advantages to their bacterial host, yet also pose a lethal threat as they can reactivate and enter a lytic cycle. DNA damage of the bacterial host is a common trigger of prophage lytic cycles. Because DNA damage is frequently experienced by bacterial pathogens exposed to host immune defenses, prophage activation may be common during infection. Investigating the consequences of prophage induction in Salmonella , we discover a prophage competition element in the Gifsy-1 prophage that we name ribonuclease effector module with ATPase, inhibitor, and nuclease (RemAIN) because it blocks the lytic cycles and release of viral particles of co-resident prophages. Intramacrophage Salmonella persisters, a subpopulation that incurs DNA damage, experience prophage reactivation and subsequent RemAIN activation, which influences Salmonella persisters and macrophage response to infection. Our findings reveal a multi-layered host-pathogen arms race in which prophage-prophage competition influences bacterial persistence and the mammalian immune response. [Display omitted] • RemAIN is an antiphage defense element encoded in a Salmonella prophage • RemAIN blocks the lytic cycles of co-residing prophages • RemAIN acts through cleavage of tRNA at the anticodon • RemAIN is active in intramacrophage Salmonella persisters Sargen and Helaine find a prophage-encoded anti-phage defense element that blocks the lytic cycles of co-residing prophages. They further find that prophage competition occurs in Salmonella persisters within macrophages, revealing a multi-layered host-pathogen arms race in which an anti-phage defense element influences bacterial persistence and the mammalian host immune response. [ABSTRACT FROM AUTHOR]

Salmonella is a foodborne pathogen of animal and public health significance. Considering the disadvantages of antibiotics or chemical preservatives traditionally used to eliminate this pathogen, attention has shifted, in recent years, toward biocontrol agents such as bacteriophages, used either separately or in combination to prevent food contamination. However, extensive use of phage-based biocontrol agents in the food industry requires further studies to ensure their safety and efficacy. In the present study, we investigated the effectiveness and safety of phage cocktail, a phage cocktail comprising three pre-characterized Salmonella phages (vB_SenS_TUMS_E4, vB_SenS_TUMS_E15 and vB_SenS_TUMS_E19). First, we performed an MTT [3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyl tetrazolium bromide] assay on a human foreskin fibroblast cell line, in which the resulting high cell viability revealed the safety of the phage cocktail. Next, we performed a time-kill assay in which a 4 Log decline in bacterial levels was detected. Additionally, we utilized a colorimetric method to evaluate the anti-biofilm activity of phage cocktail, in which it proved more efficacious compared to the MIC and MBEC levels of the antibiotic control. Then, we assessed the ability of phage cocktail to eradicate Salmonella in different food samples, where it considerably reduced the bacterial count regardless of the temperature (4°C and 25°C). Lastly, we used broiler chickens as an animal model to measure the growth-promoting activity of phage cocktail. Salmonella -infected chickens orally treated with modified phage cocktail demonstrated no mortality and a significant increase in weight gain compared to the untreated group (p ≤ 0.0002). The study presents a novel research evaluating the effectiveness and safety of a phage cocktail as a biocontrol agent against Salmonella in various contexts, including biofilms, food products, and broiler chickens. This multifaceted approach underscores the promising role of phage therapy as a sustainable biocontrol strategy in food safety and public health contexts. [ABSTRACT FROM AUTHOR]

Introduction: Salmonella , Escherichia coli , Lawsonella intracellularis , and Brachyspira hyodysenteriae are the primary pathogens responsible for gastrointestinal diseases in pigs, posing a significant threat to the health and productivity of pig production systems. Pathogen detection is a crucial tool for monitoring and managing these infections. Methods: We designed primers and probes targeting the invA gene of Salmonella , the 23S rRNA gene of Escherichia coli , the aspA gene of Lawsonella intracellularis , and the nox gene of Brachyspira hyodysenteriae. We developed a quadruplex TaqMan real-time quantitative PCR assay capable of simultaneously detecting these four pathogens. Results: This assay demonstrated high sensitivity, with detection limits of 100 copies/μL for the recombinant plasmid standards pEASY-23S rRNA, pEASY-aspA, and pEASY- nox , and 10 copies/μL for pEASY- invA. The standard curves exhibited excellent linearity (R2 values of 0.999, 0.999, 1, and 0.998, respectively) and high amplification efficiencies (93.57%, 94.84%, 85.15%, and 81.81%, respectively). The assay showed high specificity, with no cross-reactivity detected against nucleic acids from Streptococcus suis, porcine epidemic diarrhoea virus (PEDV), porcine transmissible gastroenteritis virus (TGEV), Pasteurella multocida , Clostridium perfringens , Gracilaria parapsilosis , porcine delta coronavirus (PDCoV), porcine group A rotavirus (GARV), and porcine teschovirus (PTV). The assay also exhibited excellent repeatability, with inter- and intra-assay coefficient of variation (CV) ranging from 0.15% to 1.12%. High concentrations of nucleic acids did not interfere with the detection of low concentrations, ensuring robust performance in complex samples. Among 263 diarrhoeic samples, the assay detected Salmonella in 23.95%, Escherichia coli in 26.24%, Lawsonella intracellularis in 33.84%, and Brachyspira hyodysenteriae in 22.43%. Discussion: This quadruplex TaqMan qPCR assay offers a rapid, sensitive, and specific tool for the simultaneous detection of Salmonella , Escherichia coli , Lawsonella intracellularis , and Brachyspira hyodysenteriae in pigs. [ABSTRACT FROM AUTHOR]

Paratyphoid B fever (PTB) is caused by an invasive lineage (phylogroup 1, PG1) of Salmonella enterica serotype Paratyphi B (SPB). However, little was known about the global population structure, geographic distribution, and evolution of this pathogen. Here, we report a whole-genome analysis of 568 historical and contemporary SPB PG1 isolates, obtained globally, between 1898 and 2021. We show that this pathogen existed in the 13th century, subsequently diversifying into 11 lineages and 38 genotypes with strong phylogeographic patterns. Following its discovery in 1896, it circulated across Europe until the 1970s, after which it was mostly reimported into Europe from South America, the Middle East, South Asia, and North Africa. Antimicrobial resistance recently emerged in various genotypes of SPB PG1, mostly through mutations of the quinolone-resistance-determining regions of gyrA and gyrB. This study provides an unprecedented insight into SPB PG1 and essential genomic tools for identifying and tracking this pathogen, thereby facilitating the global genomic surveillance of PTB. Hawkey et al. provide insights into the spatio-temporal distribution and genetic diversity of Salmonella Paratyphi B — the agent of paratyphoid B fever — and report a genotyping scheme facilitating the international surveillance of this pathogen. [ABSTRACT FROM AUTHOR]

Bacteria use the type VI secretion system (T6SS) to secrete toxins into pro- and eukaryotic cells via machinery consisting of a contractile sheath and a rigid tube. Rearrangement hotspot (Rhs) proteins represent one of the most common T6SS effectors. The Rhs C-terminal toxin domain displays great functional diversity, while the Rhs core is characterized by YD repeats. We elucidate the Rhs core structures of PAAR- and VgrG-linked Rhs proteins from Salmonella bongori and Advenella mimigardefordensis , respectively. The Rhs core forms a large shell of β-sheets with a negatively charged interior and encloses a large volume. The S. bongori Rhs toxin does not lead to ordered density in the Rhs shell, suggesting the toxin is unfolded. Together with bioinformatics analysis showing that Rhs toxins predominantly act intracellularly, this suggests that the Rhs core functions two-fold, as a safety feature for the producer cell and as delivery mechanism for the toxin. [Display omitted] • PAAR- and VgrG-linked Rhs form large, negatively charged shells • Rhs toxins function predominantly intracellularly, in contrast to non-Rhs toxins • TMDs, prePAAR motifs, and VIRs are not consistently present in Rhs effectors Kielkopf et al. elucidate the structures of two bacterial T6SS-associated Rhs proteins. Rhs cores form large, negatively charged shells that encapsulate unfolded or molten globule toxin domains. Their bioinformatic analyses show that Rhs toxins predominantly act intracellularly and that TMDs, prePAAR motifs, and VIRs are not consistently present in Rhs effectors. [ABSTRACT FROM AUTHOR]