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The incidence of antimicrobial resistance (AMR) in the environment is often overlooked and leads to serious health threats under the One Health paradigm. Infection with extended-spectrum β-lactamase (ESBL) producing bacteria in humans and animals has been widely examined, with the mode of transmission routes such as food, water, and contact with a contaminated environment. The purpose of this study was to determine the occurrence and molecular characteristics of resistant Salmonella enterica (S. enterica) (n = 59) and Escherichia coli (E. coli) (n = 392) isolated from produce commodities collected from fresh markets and supermarkets in Bangkok, Thailand. In this study, the S. enterica isolates exhibited the highest prevalence of resistance to tetracycline (11.9%) and streptomycin (8.5%), while the E. coli isolates were predominantly resistant to tetracycline (22.5%), ampicillin (21.4%), and sulfamethoxazole (11.5%). Among isolates of S. enterica (6.8%) and E. coli (15.3%) were determined as multidrug resistant (MDR). The prevalence of ESBL-producing isolates was 5.1% and 1.0% in S. enterica and E. coli, respectively. A minority of S. enterica isolates, where a single isolate exclusively carried blaCTX-M-55 (n = 1), and another isolate harbored both blaCTX-M-55 and blaTEM-1 (n = 1); similarly, a minority of E. coli isolates contained blaCTX-M-55 (n = 2) and blaCTX-M-15 (n = 1). QnrS (11.9%) and blaTEM (20.2%) were the most common resistant genes found in S. enterica and E. coli, respectively. Nine isolates resistant to ciprofloxacin contained point mutations in gyrA and parC. In addition, the odds of resistance to tetracycline among isolates of S. enterica were positively associated with the co-occurrence of ampicillin resistance and the presence of tetB (P = 0.001), while the E. coli isolates were positively associated with ampicillin resistance, streptomycin resistance, and the presence of tetA (P

Genetic screening of pools of mutants can reveal genetic determinants involved in complex biological interactions, processes, and systems. We previously constructed two single-gene deletion resources for Salmonella enterica serovar Typhimurium 14028s in which kanamycin (KanR) and chloramphenicol (CamR) cassettes were used to replace non-essential genes. We have now used lambda-red recombination to convert the antibiotic cassettes in these resources into a tetracycline-resistant (TetR) version where each mutant contains a different 21-base barcode flanked by Illumina Read1 and Read2 primer sequences. A motility assay of a pool of the entire library, followed by a single-tube processing of the bacterial pellet, PCR, and sequencing, was used to verify the performance of the barcoded TetR collection. The new resource is useful for experiments with defined subsets of barcoded mutant strains where biological bottlenecks preclude high numbers of founder bacteria, such as in animal infections. The TetR version of the library will also facilitate the construction of triple mutants by transduction. The resource of 6197 mutants covering 3490 genes is deposited at Biological and Emerging Infections Resources (beiresources.org).

Salmonella enterica serovars are zoonotic bacterial that cause foodborne enteritis. Due to bacteria's antibiotic resistance, using bacteriophages for biocontrol and treatment is a new therapeutic approach. In this study, we isolated, characterized, and analyzed the genome of vB_SenS_TUMS_E19 (E19), a broad host range Salmonella bacteriophage, and evaluated the influence of E19 on liquid eggs infected with Salmonella enterica serovar Enteritidis. Transmission electron microscopy showed that the isolated bacteriophage had a siphovirus morphotype. E19 showed rapid adsorption (92% in 5 min), a short latent period (18 min), a large burst size (156 PFU per cell), and a broad host range against different Salmonella enterica serovars. Whole-genome sequencing analysis indicated that the isolated phage had a 42 813 bp long genome with 49.8% G + C content. Neither tRNA genes nor those associated with antibiotic resistance, virulence factors, or lysogenic formation were detected in the genome. The efficacy of E19 was evaluated in liquid eggs inoculated with S. Enteritidis at 4 and 25 °C, and results showed that it could effectively eradicate S. Enteritidis in just 30 min and prevented its growth up to 72 h. Our findings indicate that E19 can be an alternative to a preservative to control Salmonella in food samples and help prevent and treat salmonellosis. [ABSTRACT FROM AUTHOR]

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Salmonella infections are a serious global health concern, particularly in developing countries, and are further exacerbated by the emergence of antibiotic resistance. San‐Huang‐Xie‐Xin‐Tang (SHXXT), a traditional herbal medicine with potent anti‐inflammatory properties, has recently gained attention as an alternative treatment. Our study emphasizes on the importance of precise timing in accordance with traditional Chinese medicine principles. A mouse infection model was established while different administration times of SHXXT were recorded for the body weight, clinical scores, bacterial counts in blood, and organs. Additionally, cytokine levels, fatty acids, and amino acids in the serum were also monitored. We found that administering SHXXT 1 day after Salmonella enterica subsp. enterica serovar Typhimurium (S. Typhimurium) infection (T1 group) leads to positive outcomes. This includes restoration of body weight, improved clinical scores, and reduced bacterial counts in blood and vital organs. Interferon‐gamma levels remained consistently high across all treatment groups 6 days post‐infection. However, the T1 group showed exclusive suppression of serum levels of tumor necrosis factor‐alpha (TNF‐α) and interleukin‐1 beta (IL‐1β). The timing of administration significantly influenced serum fatty acid concentrations, countering Salmonella‐induced disruptions, aligning with TNF‐α and IL‐1β levels. SHXXT had also restored amino acid profiles disrupted by the infection, with notable effects when administered at the correct timing. Our research highlights SHXXT's potential in treating S. Typhimurium infection, emphasizing the importance of precise timing in line with traditional Chinese medicine principles for effective treatment at different disease stages. [ABSTRACT FROM AUTHOR]

The speciation of Salmonella occurred by acquisition of genomic islands from other bacterial species and continued to diverge into subspecies and serovars with diferent range of host. S. enterica serovar Typhimurium (STM) is a generalist pathogen infecting hosts that include birds, mice, and humans, whilst S. enterica serovar Typhi (STY) is a restricted-host pathogen, infecting only humans. Despite their ranges of hosts, STM and STY possess 97-98% identity. Gain of genes by horizontal transference and loss of genes by mutations, are believed essential for differentiation of Salmonella. Salmonella pathogenicity island 3 (SPI-3) is an example combining these two processes. SPI-3 encodes misL and marT, among other genes. In STM, misL is required for gut colonization. Furthermore, protein MarT, positively regulates expression of misL by binding to misL-promoter. On the other hand, in SPI-3 of STY, marT and misL are pseudogenes. Interestingly, the gene t3766 (gene involved in resistance to H2O2) is present only in STY and is negatively regulated when marTSTM is heterologously expressed in STY. Based on the view that MarT might regulate genes implicated in virulence, this work searched for new genes regulated by MarT. In silico searches for possible MarT target genes were performed, and 4 genes were selected for further analysis as they contained at least 2 copies of the consensus MarT-binding sequence in their promoters. Mutating marT in STM or heterologously expressing marTSTM in STY confirmed that MarT negatively regulates ORF STY1408 or STM14_2003, its homologue in STM. STY1408 encodes for a putative protein with homology to methyl accepting chemotaxis proteins, which participate in chemotaxis and motility. Therefore, STY1408 was named mrmI (MarT-regulated motility gene I). Motility assays confirmed that the product of mrmI modulates motility. In addition, in vitro infection of cells with STM and STY mutants in mrmI reduces association with cells at 1, 3 and 24 h post-infection. Oral infection of mice showed that a mrmI null mutant was defective in producing systemic disease. Therefore, we conclude that MarT regulated mrmI, is involved in virulence of Salmonella. While pseudogenization of marT might modulate the fitness of narrow host range STY. [ABSTRACT FROM AUTHOR]

Salmonella enterica is a foodborne pathogen associated with both typhoid and non-typhoid illness in humans and animals. This problem is further exacerbated by the emergence of antibiotic-resistant strains of Salmonella enterica. Therefore, to meet public health and safety, there is a need for an alternative strategy to tackle antibiotic-resistant bacteria. Bacteriophages or (bacterial viruses), due to their specificity, self-dosing, and antibiofilm activity, serve as a better approach to fighting against drug-resistant bacteria. In the current study, a broad-host range lytic phage phiSalP219 was isolated against multidrugresistant Salmonella enterica serotypes Paratyphi from a pond water sample. Salmonella phage phiSalP219 was able to lyse 28/30 tested strains of Salmonella enterica. Salmonella phage phiSalP219 exhibits activity in acidic environments (pH3) and high temperatures (70°C). Electron microscopy and genome analysis revealed that phage phiSalP219 is a member of class Caudoviricetes. The genome of Salmonella phage phiSalP219 is 146Kb in size with 44.5% GC content. A total of 250 Coding Sequence (CDS) and 25 tRNAs were predicted in its genome. Predicted open reading frames (ORFs) were divided into five groups based on their annotation results: (1) nucleotide metabolism, (2) DNA replication and transcription, (3) structural proteins, (4) lysis protein, and (5) other proteins. The absence of lysogeny-related genes in their genome indicates that Salmonella phage phiSalP219 is lytic in nature. Phage phiSalP219 was also found to be microbiologically safe (due to the absence of toxin or virulence-related genes) in the control of Salmonella enterica serovar Typhimurium infections in the ready-to-eat meat and also able to eradicate biofilm formed by the same bacterium on the borosilicate glass surface. [ABSTRACT FROM AUTHOR]

Contamination of poultry products by Salmonella enterica serovar Typhimurium (STm) is a major cause of foodborne infections and outbreaks. This study aimed to assess the diversity and antimicrobial resistance (AMR) carriage of STm in three chicken processing plants using genomic sequencing. It also aimed to investigate whether any particular strain types were associated with cases of human illness. Multilevel genome typing (MGT) was used to analyze 379 STm isolates from processed chicken carcasses. The diversity of chicken STm sequence types (STs) increased from MGT1 (2 STs) to MGT9 (257 STs). STs at MGT5 to MGT9 levels that were unique to one processing plant and shared among the processing plants were identified, likely reflecting the diversity of STm at their farm source. Fifteen medium resolution MGT5 STs matched those from human infections in Australia and globally. However, no STs matched between the chicken and human isolates at high resolution levels (MGT8 or MGT9), indicating the two STm populations were phylogenetically related but were unlikely to be directly epidemiologically linked. AMR genes were rare, with only a blaTEM-1 gene carried by a 95 kb IncI1 Alpha plasmid being identified in 20 isolates. In conclusion, subpopulations that were widespread in processing plants and had caused human infections were described using MGT5 STs. In this STM population, AMR was rare with only sporadic resistance to a single drug class observed. The genomic analysis of STm from chicken processing plants in this study provided insights into STm that contaminate meat chickens early in the food production chain. [ABSTRACT FROM AUTHOR]

Rapid and accurate identification of Salmonella enterica serotypes Typhi and Paratyphi (A, B and C), the causal agents of enteric fever, is critical for timely treatment, case management and evaluation of health policies in low and middle-income countries where the disease still remains a serious public health problem. The present study describes the development of a multiplex assay (EFMAtyping) for simultaneous identification of pathogens causing typhoid and paratyphoid fever in a single reaction by the MeltArray approach, which could be finished within 2.5 h. Seven specific genes were chosen for differentiation of typhoidal and nontyphoidal Salmonella. All gene targets were able to be detected by the EFMAtyping assay, with expected Tm values and without cross-reactivity to other relevant Salmonella serovars. The limit of detection (LOD) for all gene targets was 50 copies per reaction. The LOD reached 102–103 CFU/ml for each pathogen in simulated clinical samples. The largest standard deviation value for mean Tm was below 0.5 °C. This newly developed EFMAtyping assay was further evaluated by testing 551 clinical Salmonella isolates, corroborated in parallel by the traditional Salmonella identification workflow, and serotype prediction was enabled by whole-genome sequencing. Compared to the traditional method, our results exhibited 100% of specificity and greater than 96% of sensitivity with a kappa correlation ranging from 0.96 to 1.00. Thus, the EFMAtyping assay provides a rapid, high throughput, and promising tool for public health laboratories to monitor typhoid and paratyphoid fever. [ABSTRACT FROM AUTHOR]

In mammals, enteric salmonellas can use tetrathionate (ttr), formed as a by-product from the inflammatory process in the intestine, as electron acceptor in anaerobic respiration, and it can fuel its energy metabolism by degrading the microbial fermentation product 1,2-propanediol. However, recent studies have shown that this mechanism is not important for Salmonella infection in the intestine of poultry, while it prolongs the persistence of Salmonella at systemic sites in this species. In the current study, we show that ΔttrApduA strains of Salmonella enterica have lower net survival within chicken-derived HD-11 macrophages, as CFU was only 2.3% (S. Enteritidis ΔttrApduA), 2.3% (S. Heidelberg ΔttrApduA), and 3.0% (S. Typhimurium ΔttrApduA) compared to wild-type strains after 24 h inside HD-11 macrophage cells. The difference was not related to increased lysis of macrophages, and deletion of ttrA and pduA did not impair the ability of the strains to grow anaerobically. Further studies are indicated to determine the reason why Salmonella ΔttrApduA strains survive less well inside macrophage cell lines. [ABSTRACT FROM AUTHOR]

Simple Summary: One of the main concerns associated with phage applications is the potential emergence of bacterial variants exhibiting reduced susceptibility to bacteriophages, which may jeopardize the success of such applications, as occurs with antibiotics. In this work, we studied the emergence of reduced-phage-susceptibility variants in broiler trials challenged with Salmonella enterica serovar Infantis and treated with the PhagoVet product. We characterized the bacteriophages composing the PhagoVet product at both a microscopic and genomic level, which displayed a broad host range of infection against 271 strains representing 18 Salmonella serovars. Our results indicate that the emergence of reduced-phage-susceptibility variants is unlikely to compromise the efficacy of oral PhagoVet against S. Infantis. Salmonella enterica serovar Infantis (S. Infantis) poses a growing issue in the poultry sector, with phage-based products emerging as a safe and effective control measure. This study investigated the emergence of reduced-phage-susceptibility variants (RPSV) of S. Infantis in PhagoVet-treated broilers, given that RPSV could undermine phage treatment efficacy. The bacteriophages in the PhagoVet product were characterized using transmission electron microscopy (TEM), genome sequencing, and infection profiling. Furthermore, two broiler trials were conducted: a challenge group (T1) and a challenge-and-treated group (T2). The S. Infantis infective dose was set at 104 and 106 colony-forming units (CFUs) per animal, with PhagoVet administration at 106 and 108 plaque-forming units (PFUs) per animal, in Trials 1 and 2, respectively. The results revealed that the four PhagoVet bacteriophages belonged to different genera. PhagoVet evidenced broad-spectrum efficacy against 271 strains representing 18 Salmonella serovars. In Trial 1, PhagoVet reduced bacterial counts in feces to nearly undetectable levels by day 42, with no RPSV detected. However, in Trial 2, three and five RPSVs were detected in feces and ceca, respectively. Consequently, PhagoVet demonstrated efficacy against S. Infantis in broilers, and the potential impact of RPSV is deemed unlikely to compromise its efficacy. [ABSTRACT FROM AUTHOR]

Kombucha, a beverage traditionally obtained through the fermentation of tea, is believed to have beneficial health properties. Therefore, characterizing the microorganisms responsible for this fermentation is essential to demonstrate its potential health benefits and to identify candidates for new probiotics. In this study, four probiotic yeast strains isolated from kombucha tea were identified, by the PCR-RFLP analysis of the ribosomal ITS region and the sequence of the D1/D2 domain of the 26S rDNA, as Brettanomyces bruxellensis (UVI55 and UVI56) and B. anomalus (UVI57 and UVI58). Properties relevant to probiotics were also studied in these strains. All of them showed excellent survival in simulated gastric (99%-100%) and duodenal (95%-100%) juices. The ability to self-aggregate (38%-100%), adhesion to xylene (15%-50%) and, above all, adhesion to Caco-2 cells (4%-21%), revealed its potential capacity to adhere to the intestinal epithelium. In addition, the tested strains showed excellent antioxidant capacity (82%-94%), antimicrobial activity against different pathogens (Escherichia coli, Staphylococcus aureus, Salmonella enterica, Listeria monocytogenes, and Bacillus cereus), as well as remarkable cytotoxic activity against colon, melanoma and ovarian tumor cell lines. Finally, using Caenorhabditis elegans as a model, strain UVI56 exhibited ability to both extend the lifespan of the nematode and protect it against infection by S. enterica. These results support the probiotic and functional properties of the analyzed strains. In conclusion, the study revealed that kombucha tea could be a source of potential probiotics that contribute to its health-promoting properties and that the characterized Brettanomyces strains could be exploited directly as probiotics or for the development of new functional foods. [ABSTRACT FROM AUTHOR]

Bacteriocins produced by a number of lactic acid bacteria (LAB) comprise a variety of antimicrobial proteins that may be used as antibiotic alternative in food preservation. The present study aimed to isolate and characterize LAB-derived bacteriocin-like substances (BLS) from local fermented foods. A total of twenty-one bacterial strains were isolated and subjected to an antibacterial assay. Five isolates designated as AB1, AB2, AK1, AK2, AnK1 showed inhibitory activity against selected indicator organisms and were subjected to further characterization. Upon BLAST analysis of the 16S rRNA gene sequences, the isolates showed close relationship to Lactobacillus plantarum with similarity ranging from 91 to 97%. Moreover, the antibacterial metabolite production of the isolates was observed to peak on the 5th to 7th day of incubation. Since AnK1 showed the highest zone of inhibition among 5 isolates, it was selected for characterization of the BLS isolated by ammonium sulfate precipitation and anion exchange chromatography. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that the AnK1-BLS had a single band and a molecular weight around 15 kDa, and a total protein concentration of 7.06 µg/mL. Interestingly, AnK1-BLS had a broad antimicrobial spectrum on both gram-negative and gram-positive food-borne pathogens, including Escherichia coli, Salmonella enterica, Pseudomonas aeruginosa, and Bacillus subtilis. Moreover, the purified AnK1-BLS exhibited good thermal stability when heated at 80‒121°C. Likewise, its inhibitory activity was not affected by pH in the range of 3.0 to 6.5, with maximum activity recorded at pH 3.0. The results suggest that AnK1-BLS may have application prospects in the food industry. Further studies on the complete protein characterization of AnK1-BLS is recommended to fully harness its capabilities. [ABSTRACT FROM AUTHOR]

Salmonellosis associated with reptiles is a well‐researched topic, particularly in China and the United States, but it occurs less frequently in Europe. The growth of the human population and changes in the environment could potentially increase the interaction between humans and free‐living reptiles, which are an unidentified source of Salmonella species. In this study, we sought to explore this issue by comparing the microbiota of free‐living European grass snakes, scientifically known as Natrix natrix, with that of captive banded water snakes, or Nerodia fasciata. We were able to isolate 27 strains of Salmonella species from cloacal swabs of 59 N. natrix and 3 strains from 10 N. fasciata. Our findings revealed that free‐living snakes can carry strains of Salmonella species that are resistant to normal human serum (NHS). In contrast, all the Salmonella species strains isolated from N. fasciata were sensitive to the action of the NHS, further supporting our findings. We identified two serovars from N. natrix: Salmonella enterica subspecies diarizonae and S. enterica subspecies houtenae. Additionally, we identified three different virulotypes (VT) with invA, sipB, prgH, orgA, tolC, iroN, sitC, sifA, sopB, spiA, cdtB and msgA genes, and β‐galactosidase synthesised by 23 serovars. The identification of Salmonella species in terms of their VT is a relatively unknown aspect of their pathology. This can be specific to the serovar and pathovar and could be a result of adaptation to a new host or environment. [ABSTRACT FROM AUTHOR]

Aims: Our aim is to characterize through whole‐genome sequencing (WGS) the antimicrobial resistance (AMR) and heavy metal tolerance (HMT) genes content, plasmid presence, virulence potential and genomic diversity of the rare non‐typhoid Salmonella enterica serovar Orion (S. Orion) from 19 countries of the African, American, Eastern Mediterranean, European, Southeastern Asia and Western Pacific regions. Methods and Results: Totally 324 S. Orion genomes were screened for AMR, HMT and virulence genes, plasmids and Salmonella Pathogenicity Islands (SPIs). Genomic diversity was investigated using Multi‐Locus Sequence Typing (MLST) and core‐genome MLST (cgMLST). Efflux pump encoding genes mdsA and mdsB were present in all genomes analysed, while quinolone chromosomal point mutations and aminoglycoside, beta‐lactam, colistin, lincosamide, macrolide, phenicol, sulphonamide, trimethoprim, tetracycline and disinfectant resistance genes were found in 0.3%–5.9%. A total of 17 genomes (5.2%) from Canada, the United Kingdom, the USA and Tanzania showed a potential multi‐drug resistance profile. Gold tolerance genes golS and golT were detected in all genomes analysed, while arsenic, copper, mercury, silver and tellurium tolerance genes were found in 0.3%–35.5%. Col(MGD2) was the most frequently detected plasmid, in 15.4% of the genomes. Virulence genes related to adherence, macrophage induction, magnesium uptake, regulation, serum resistance, stress adaptation, type III secretion systems and six SPIs (1, 2, 3, 4, 5, 9, 12, 13, 14 and C63PI) were detected. ST639 was assigned to 89.2% of the S. Orion genomes, while cgMLST showed core‐genome STs and clusters of strains specific by countries. Conclusion: The high virulence factor frequencies, the genomic similarity among some non‐clinical and clinical strains circulating worldwide and the presence of a strain carrying a resistance gene against a last resource antimicrobial like colistin, highlight the potential risk of S. Orion strains for public health and food safety and reinforce the importance to not underestimate the potential hazard of rare non‐typhoid Salmonella serovars. [ABSTRACT FROM AUTHOR]

1. Epidemiological surveillance of Salmonella spp. serves as a primary tool for maintaining the health of poultry flocks. Characterising circulating serotypes is crucial for implementing control and prevention measures. This study conducted phenotypic and molecular characterisation of S. enterica Pullorum, S. enterica Heidelberg, and S. enterica Corvalis isolated from broiler chickens during slaughtering. 2. All strains were susceptible to gentamicin, neomycin and norfloxacin. However, resistance rates exceeded 50% for ciprofloxacin and tiamulin, irrespective of the serotype. Approximately 64% of strains were classified as multidrug-resistant, with S. enterica Heidelberg strains exhibiting significantly higher overall resistance. The isolates demonstrated the ability to adhere and produce biofilm at a minimum of three temperatures, with S. enterica Pullorum capable of biofilm production at all temperatures encountered during poultry rearing. 3. Each strain possessed between two and seven different virulence-associated genes. Genetic similarity, as indicated by pulsed field gel electrophoresis, exceeded 90% for all three serotypes and strains were classified in the R5 ribotype by PCR, regardless of serotype. Sequencing revealed high similarity among all strains, with homology ranging from 99.61 to 100% and all were classified to a single cluster. 4. The results suggested a clonal relationship among the strains, indicating the possible circulation of a unique clonal group of S. enterica Pullorum in the southern region of Brazil. [ABSTRACT FROM AUTHOR]

Salmonella enterica subsp. enterica serotype Enteritidis (S. Enteritidis) is one of the major causes of foodborne infections and is responsible for many national and multi-country foodborne outbreaks worldwide. In Greece, human salmonellosis is a mandatory notifiable disease, with laboratory surveillance being on a voluntary basis. This study aims to provide the first insights into the genetic characteristics and antimicrobial resistance profiles of 47 S. Enteritidis human isolates using whole-genome sequencing (WGS) technology. The S. Enteritidis population was mainly resistant to fluoroquinolones due to gyrA point mutations, whereas one isolate presented a multi-resistant plasmid-mediated phenotype. ST11 was the most frequent sequence type, and phylogenetic analysis through the cgMLST and SNP methods revealed considerable genetic diversity. Regarding virulence factors, 8 out of the 24 known SPIs and C63PI were detected. Due to the observed variability between countries, it is of utmost importance to record the circulating S. Enteritidis strains' structure and genomic epidemiology at the national level. WGS is a valuable tool that is revolutionizing our approach to Salmonella by providing a deeper understanding of these pathogens and their impact on human health. [ABSTRACT FROM AUTHOR]

Antibiotic misuse has led to the development and spread of multidrug-resistant (MDR) microorganisms. This study evaluated the antibacterial activity of n-hexane, ethyl acetate, and aqueous extracts of the marine sponge Amphimidon chloros. The antibacterial activity of n-hexane, ethyl acetate, and aqueous extracts was evaluated using broth microdilution and disc diffusion. The chemical composition of the extracts was analysed using Liquid Chromatography-Mass spectrometry (LC-MS). The antibacterial potency of the extracts was in the following order: aqueous > n-hexane > ethyl acetate extracts. The most significant inhibitory activity of the aqueous extract was against Shigella flexneri, with an inhibition zone of 20.6 mm. Klebsiella pneumonia, Pseudomonas aeruginosa, and Listeria monocytogenes were utterly resistant to ampicillin and chloramphenicol; however, the aqueous extract efficiently inhibited these bacteria. The extract MIC ranged from 0.0195-2.5 mg/mL. With maximal inhibition against Staphylococcus aureus (0.0195 mg/mL), Bacillus cereus (0.0390 mg/mL), Shigella flexneri (0.0390 mg/mL), and Salmonella enterica (0.0781 mg/mL). While L. monocytogenes (0.3125 mg/mL) and S. aureus (0.625 mg/mL) were the only Gram-positive bacteria inhibited, the ethyl acetate extract was equally effective (MIC of 0.3125 mg/mL) against Gram-negative bacteria, including K. pneumonia, S. typhi, S. enterica, Enterobacter aerogenes, and E. coli. The n-hexane extract inhibited S. aureus, S. flexneri, and S. enterica with a MIC value of 0.1562/mL. The most prevalent phytochemicals in the aqueous and n-hexane extracts from the LC-MS study were nakinadine and kermaphidine. The study revealed that the aqueous extract of A. chloros possesses both Gram-positive and Gram-negative antibacterial activity. [ABSTRACT FROM AUTHOR]

Since the use of antibiotics as growth promoters in animal feed has been restricted or banned in several countries, finding suitable alternatives is crucial for maintaining animal health. In this study, a novel formate acidifier named sodium diformate (NaDF) was synthesized, and the effects on growth performance and the prevention effects against Salmonella enterica serovar Pullorum infections in chickens were assessed. In broilers, NaDF supplementation improved growth performance, as evidenced by increased body weights and reduced feed conversion ratios. At 38 days of age, NaDF supplementation increased the levels of growth-hormone and ghrelin in the serum, lowered pH values in the gut, improved duodenal morphology, as shown by increased villus length/crypt depth ratios. NaDF also modulated the abundance of beneficial and harmful bacteria without changing the general microbiota diversity and short-chain fatty acids levels, which would be beneficial for maintaining gut homeostasis during its use. NaDF exhibited a broad spectrum of antibacterial activity in vitro. Supplementation with NaDF effectively decreased S. Pullorum colonization in the cecum, liver and spleen in chickens, and mitigated pathological changes in the tissues. Therefore, as a novel acidifier, NaDF can improve chicken growth performance by increasing growth-related hormones levels while maintaining the diversity of gut microbiota, and also resist intestinal bacterial infection. These results provided evidences for the application of NaDF as an effective and safe animal feed in poultry farming. [ABSTRACT FROM AUTHOR]

Campylobacter jejuni is a common foodborne pathogen found in poultry that can cause severe life-threatening illnesses in humans. It is important to detect this pathogen in food to manage foodborne outbreaks. This study reports a novel impedimetric phage protein-based biosensor to detect C. jejuni NCTC 11168 at 100 CFU/mL concentrations using a genetically engineered receptor-binding phage protein, FlaGrab, as a bioreceptor. The electrochemical impedance spectroscopy (EIS) technique was employed to measure changes in resistance upon interaction with C. jejuni. The sensitivity of the phage protein-immobilized electrode was assessed using the various concentrations of C. jejuni NCTC 11168 ranging from 102–109 colony forming units (CFU)/mL). The change transfer resistance of the biosensor increased with increasing numbers of C. jejuni NCTC 11168 cells. The detection limit was determined to be approximately 103 CFU/mL in the buffer and 102 CFU/mL in the ex vivo samples. Salmonella enterica subsp. enterica serotype Typhimurium-291RH and Listeria monocytogenes Scott A were used as nontarget bacterial cells to assess the specificity of the developed biosensor. Results showed that the developed biosensor was highly specific toward the target C. jejuni NCTC 11168, as no signal was observed for the nontarget bacterial cells. [ABSTRACT FROM AUTHOR]

Whole genome sequencing is replacing traditional laboratory surveillance methods as the primary tool to track and characterize clusters and outbreaks of the foodborne and zoonotic pathogen Salmonella enterica (S. enterica). In this study, 438 S. enterica isolates representing 35 serovars and 13 broad vehicle categories from one hundred epidemiologically confirmed outbreaks were evaluated for genetic variation to develop epidemiologically relevant interpretation guidelines for Salmonella disease cluster detection. The Illumina sequences were analyzed by core genome multi-locus sequence typing (cgMLST) and screened for antimicrobial resistance (AR) determinants and plasmids. Ninety-three of the one hundred outbreaks exhibited a close allele range (less than 10 allele differences with a subset closer than 5). The remaining seven outbreaks showed increased variation, of which three were considered polyclonal. A total of 16 and 28 outbreaks, respectively, showed variations in the AR and plasmid profiles. The serovars Newport and I 4,[5],12:i:-, as well as the zoonotic and poultry product vehicles, were overrepresented among the outbreaks, showing increased variation. A close allele range in cgMLST profiles can be considered a reliable proxy for epidemiological relatedness for the vast majority of S. enterica outbreak investigations. Variations associated with mobile elements happen relatively frequently during outbreaks and could be reflective of changing selective pressures. [ABSTRACT FROM AUTHOR]

Controlling foodborne pathogens in buffalo milk is crucial for ensuring food safety. This study estimated the prevalence of nine target genes representing seven critical foodborne bacteria in milk and milk products, and identified factors associated with their presence in buffalo milk chain nodes in Bangladesh. One hundred and forty-three milk samples from bulk tank milk (n = 34), middlemen (n = 37), milk collection centers (n = 37), and milk product shops (n = 35) were collected and analyzed using RT-PCR. Escherichia (E.) coli, represented through yccT genes, was the most prevalent throughout the milk chain (81–97%). Chi-squared tests were performed to identify the potential risk factors associated with the presence of foodborne bacteria encoded for different genes. At the middleman level, the prevalence of E. coli was associated with the Mymensingh, Noakhali, and Bhola districts (P = 0.01). The prevalence of Listeria monocytogenes, represented through inlA genes, and Yersinia (Y.) enterocolitica, represented through yst genes, were the highest at the farm level (65–79%). The prevalence of both bacteria in bulk milk was associated with the Noakhali and Bhola districts (P < 0.05). The prevalence of Y. enterocolitica in bulk milk was also associated with late autumn and spring (P = 0.01) and was higher in buffalo-cow mixed milk than in pure buffalo milk at the milk collection center level (P < 0.01). The gene stx2 encoding for Shiga toxin-producing (STEC) E. coli was detected in 74% of the milk products. At the middleman level, the prevalence of STEC E. coli was associated with the use of cloths or tissues when drying milk containers (P = 0.01). Salmonella enterica, represented through the presence of invA gene, was most commonly detected (14%) at the milk collection center. The use of plastic milk containers was associated with a higher prevalence of Staphylococcus aureus, represented through htrA genes, at milk product shops (P < 0.05). These results suggest that raw milk consumers in Bangladesh are at risk if they purchase and consume unpasteurized milk. [ABSTRACT FROM AUTHOR]

Most Escherichia coli isolates from humans do not utilize D-sucrose as a substrate for fermentation or growth. Previous work has shown that the Csc pathway allows some E. coli to utilize sucrose for slow growth, and this pathway has been engineered in E. coli W strains to enhance use of sucrose as a feedstock for industrial applications. An alternative sucrose utilization pathway, Scr, was first identified in Klebsiella pneumoniae and has been reported in some E. coli and Salmonella enterica isolates. We show here that the Scr pathway is native to an important subset of E. coli phylogroup B2 lineages that lack the Csc pathway but grow rapidly on sucrose. Laboratory E. coli strains derived from MG1655 (phylogroup A, ST10) are unable to utilize sucrose and lack the scr and csc genes, but a recombinant plasmid-borne scr locus enables rapid growth on and fermentation of sucrose. Genome analyses of Enterobacteriaceae indicate that the scr locus is widespread in other Enterobacteriaceae; including Enterobacter and Klebsiella species, and some Citrobacter and Proteus species. In contrast, the Csc pathway is limited mostly to E. coli, some Shigella species (in which csc loci are rendered non-functional by various mutations), and Citrobacter freundii. The more efficient Scr pathway likely has greater potential than the Csc pathway for bioindustrial applications of E. coli and other Enterobacteriaceae using sucrose as a feedstock. [ABSTRACT FROM AUTHOR]

Simple Summary: Salmonellosis represents a considerable public and animal health concern. Cattle and particularly calves can be affected by this infection, which can cause a variety of clinical problems. At present, data about the diffusion of Salmonella spp. in dairy cattle farms of northern Italy are scarce. In this context, this study aims to conduct a retrospective survey on the presence of Salmonella serotypes in dairy cattle farms in the Cremona and Mantua provinces of the Lombardy Region (northern Italy). The results highlight that in most cases, Salmonella spp. was detected in the carcasses or organs of calves and that its presence was widely distributed on the farm. Finally, the analyses of antimicrobial resistance patterns place the attention on the spread of multi-drug resistant Salmonella strains. The presence of Salmonella spp. in dairy cattle farms poses a major risk to animal health and welfare. This study focused on Salmonella detection in dairy farms located in the Cremona and Mantua provinces (northern Italy) in samples collected and submitted to laboratories in 2021–2022. A total of 2710 samples from different sources, including calf carcasses/organs (n = 128), rectal swabs (n = 1937), feces (n = 390), bulk milk (n = 93), and overshoes/swabs (n = 127) for environmental sampling, were analyzed for the presence of Salmonella spp. and were included in the present study. Our results indicate that Salmonella was most commonly firstly identified from calf carcasses and organs (61.67%) and that the serotypes most frequently detected in dairies were S. Dublin (38.33%), S. Typhimurium (23.33%), and S. Typhimurium monophasic variant (14.17%). The most common pathological findings in calf carcasses were enteritis, hepatosplenomegaly, and pneumonia. The antimicrobial resistance pattern analyzed using the MIC assay of 51 Salmonella isolates revealed the presence of multi-resistant strains, which pose a major risk to public and animal health. [ABSTRACT FROM AUTHOR]

The bacterial flagellum, which facilitates motility, is composed of ~20 structural proteins organized into a long extracellular filament connected to a cytoplasmic rotor-stator complex via a periplasmic rod. Flagellum assembly is regulated by multiple checkpoints that ensure an ordered gene expression pattern coupled to the assembly of the various building blocks. Here, we use epifluorescence, super-resolution, and transmission electron microscopy to show that the absence of a periplasmic protein (FlhE) prevents proper flagellar morphogenesis and results in the formation of periplasmic flagella in Salmonella enterica. The periplasmic flagella disrupt cell wall synthesis, leading to a loss of normal cell morphology resulting in cell lysis. We propose that FlhE functions as a periplasmic chaperone to control assembly of the periplasmic rod, thus preventing formation of periplasmic flagella. The bacterial flagellum is a complex macromolecular structure that requires a highly regulated assembly of building blocks. Here, Halte et al. show that a protein controls assembly of the flagellum's periplasmic rod and prevents misformation of flagella in the periplasm. [ABSTRACT FROM AUTHOR]

As bacteriophages continue to gain regulatory approval for personalized human therapy against antibiotic-resistant infections, there is a need for transformative technologies for rapid target identification through multiple, large, decentralized therapeutic phages biobanks. Here, we design a high throughput phage screening platform comprised of a portable library of individual shelf-stable, ready-to-use phages, in all-inclusive solid tablets. Each tablet encapsulates one phage along with luciferin and luciferase enzyme stabilized in a sugar matrix comprised of pullulan and trehalose capable of directly detecting phage-mediated adenosine triphosphate (ATP) release through ATP bioluminescence reaction upon bacterial cell burst. The tablet composition also enhances desiccation tolerance of all components, which should allow easier and cheaper international transportation of phages and as a result, increased accessibility to therapeutic phages. We demonstrate high throughput screening by identifying target phages for select multidrug-resistant clinical isolates of Pseudomonas aeruginosa, Salmonella enterica, Escherichia coli, and Staphylococcus aureus with targets identified within 30-120 min. Phage therapy often relies on labour-intensive and time-consuming methods that could lead to delays in medical treatment. Here, authors describe an all-in-one solution for navigating multiple, large, decentralized biobanks, allowing for rapid high-throughput phage susceptibility testing. [ABSTRACT FROM AUTHOR]

Extraintestinal Pathogenic Escherichia coli (ExPEC) pose a significant threat to human and animal health. However, the diversity and antibiotic resistance of animal ExPEC, and their connection to human infections, remain largely unexplored. The study performs large-scale genome sequencing and antibiotic resistance testing of 499 swine-derived ExPEC isolates from China. Results show swine ExPEC are phylogenetically diverse, with over 80% belonging to phylogroups B1 and A. Importantly, 15 swine ExPEC isolates exhibit genetic relatedness to human-origin E. coli strains. Additionally, 49 strains harbor toxins typical of enteric E. coli pathotypes, implying hybrid pathotypes. Notably, 97% of the total strains are multidrug resistant, including resistance to critical human drugs like third- and fourth-generation cephalosporins. Correspondingly, genomic analysis unveils prevalent antibiotic resistance genes (ARGs), often associated with co-transfer mechanisms. Furthermore, analysis of 20 complete genomes illuminates the transmission pathways of ARGs within swine ExPEC and to human pathogens. For example, the transmission of plasmids co-harboring fosA3, blaCTX-M-14, and mcr-1 genes between swine ExPEC and human-origin Salmonella enterica is observed. These findings underscore the importance of monitoring and controlling ExPEC infections in animals, as they can serve as a reservoir of ARGs with the potential to affect human health or even be the origin of pathogens infecting humans. Extraintestinal pathogenic E. coli (ExPEC) is a significant cause of human and animal disease. Here, the authors compile a collection of 499 ExPEC samples from swine in China and characterise their phylogenetic population structure and antibiotic resistance profiles. [ABSTRACT FROM AUTHOR]

Background: Oxford Nanopore provides high throughput sequencing platforms able to reconstruct complete bacterial genomes with 99.95% accuracy. However, even small levels of error can obscure the phylogenetic relationships between closely related isolates. Polishing tools have been developed to correct these errors, but it is uncertain if they obtain the accuracy needed for the high-resolution source tracking of foodborne illness outbreaks. Results: We tested 132 combinations of assembly and short- and long-read polishing tools to assess their accuracy for reconstructing the genome sequences of 15 highly similar Salmonella enterica serovar Newport isolates from a 2020 onion outbreak. While long-read polishing alone improved accuracy, near perfect accuracy (99.9999% accuracy or ~ 5 nucleotide errors across the 4.8 Mbp genome, excluding low confidence regions) was only obtained by pipelines that combined both long- and short-read polishing tools. Notably, medaka was a more accurate and efficient long-read polisher than Racon. Among short-read polishers, NextPolish showed the highest accuracy, but Pilon, Polypolish, and POLCA performed similarly. Among the 5 best performing pipelines, polishing with medaka followed by NextPolish was the most common combination. Importantly, the order of polishing tools mattered i.e., using less accurate tools after more accurate ones introduced errors. Indels in homopolymers and repetitive regions, where the short reads could not be uniquely mapped, remained the most challenging errors to correct. Conclusions: Short reads are still needed to correct errors in nanopore sequenced assemblies to obtain the accuracy required for source tracking investigations. Our granular assessment of the performance of the polishing pipelines allowed us to suggest best practices for tool users and areas for improvement for tool developers. [ABSTRACT FROM AUTHOR]

Objectives: The emergence of multidrug-resistant (MDR) Salmonella strains, especially resistant ones toward critically important antimicrobial classes such as fluoroquinolones and third- and fourth-generation cephalosporins, is a growing public health concern. The current study, therefore, aimed to determine the prevalence, and existence of virulence genes (invA, stn, and spvC genes), antimicrobial resistance profiles, and the presence of β-lactamase resistance genes (blaOXA, blaCTX-M1, blaSHV, and blaTEM) in Salmonella strains isolated from native chicken carcasses in Egypt marketed in Mansoura, Egypt, as well as spotlight the risk of isolated MDR, colistin-, cefepime-, and levofloxacin-resistant Salmonella enterica serovars to public health. Methods: One hundred fifty freshly dressed native chicken carcasses were collected from different poultry shops in Mansoura City, Egypt between July 2022 and November 2022. Salmonella isolation was performed using standard bacteriological techniques, including pre-enrichment in buffered peptone water (BPW), selective enrichment in Rappaport Vassiliadis broth (RVS), and cultivating on the surface of xylose-lysine-desoxycholate (XLD) agar. All suspected Salmonella colonies were subjected to biochemical tests, serological identification using slide agglutination test, and Polymerase Chain Reaction (PCR) targeting the invasion A gene (invA; Salmonella marker gene). Afterward, all molecularly verified isolates were screened for the presence of virulence genes (stn and spvC). The antimicrobial susceptibility testing for isolated Salmonella strains towards the 16 antimicrobial agents tested was analyzed by Kirby–Bauer disc diffusion method, except for colistin, in which the minimum inhibition concentration (MIC) was determined by broth microdilution technique. Furthermore, 82 cefotaxime-resistant Salmonella isolates were tested using multiplex PCR targeting the β-lactamase resistance genes, including blaOXA, blaCTX-M1, blaSHV, and blaTEM genes. Results: Salmonella enterica species were molecularly confirmed via the invA Salmonella marker gene in 18% (27/150) of the freshly dressed native chicken carcasses. Twelve Salmonella serotypes were identified among 129 confirmed Salmonella isolates with the most predominant serotypes were S. Kentucky, S. Enteritidis, S. Typhimurium, and S. Molade with an incidence of 19.4% (25/129), 17.1% (22/129), 17.1% (22/129), and 10.9% (14/129), respectively. All the identified Salmonella isolates (n = 129) were positive for both invA and stn genes, while only 31.8% (41/129) of isolates were positive for the spvC gene. One hundred twenty-one (93.8%) of the 129 Salmonella-verified isolates were resistant to at least three antibiotics. Interestingly, 3.9%, 14.7%, and 75.2% of isolates were categorized into pan-drug-resistant, extensively drug-resistant, and multidrug-resistant, respectively. The average MAR index for the 129 isolates tested was 0.505. Exactly, 82.2%, 82.2%, 63.6%, 51.9%, 50.4%, 48.8%, 11.6%, and 10.1% of isolated Salmonella strains were resistant to cefepime, colistin, cefotaxime, ceftazidime/clavulanic acid, levofloxacin, ciprofloxacin, azithromycin, and meropenem, respectively. Thirty-one out (37.8%) of the 82 cefotaxime-resistant Salmonella isolates were β-lactamase producers with the blaTEM as the most predominant β-lactamase resistance gene, followed by blaCTX-M1 and blaOXA genes, which were detected in 21, 16, and 14 isolates respectively). Conclusion: The high prevalence of MDR-, colistin-, cefepime-, and levofloxacin-resistant Salmonella serovars among Salmonella isolates from native chicken is alarming as these antimicrobials are critically important in treating severe salmonellosis cases and boost the urgent need for controlling antibiotic usage in veterinary and human medicine to protect public health. [ABSTRACT FROM AUTHOR]

Objectives To characterize the genetic basis of azithromycin resistance in Escherichia coli and Salmonella collected within the EU harmonized antimicrobial resistance (AMR) surveillance programme in 2014–18 and the Danish AMR surveillance programme in 2016–19. Methods WGS data of 1007 E. coli [165 azithromycin resistant (MIC > 16 mg/L)] and 269 Salmonella [29 azithromycin resistant (MIC > 16 mg/L)] were screened for acquired macrolide resistance genes and mutations in rplDV , 23S rRNA and acrB genes using ResFinder v4.0, AMRFinder Plus and custom scripts. Genotype–phenotype concordance was determined for all isolates. Transferability of mef (C)- mph (G)-carrying plasmids was assessed by conjugation experiments. Results mph (A), mph (B), mef (B), erm (B) and mef (C)- mph (G) were detected in E. coli and Salmonella , whereas erm (C), erm (42), ere (A) and mph (E)- msr (E) were detected in E. coli only. The presence of macrolide resistance genes, alone or in combination, was concordant with the azithromycin-resistant phenotype in 69% of isolates. Distinct mph (A) operon structures were observed in azithromycin-susceptible (n  = 50) and -resistant (n  = 136) isolates. mef (C)- mph (G) were detected in porcine and bovine E. coli and in porcine Salmonella enterica serovar Derby and Salmonella enterica 1,4, [5],12:i:-, flanked downstream by IS CR2 or Tn As1 and associated with IncIγ and IncFII plasmids. Conclusions Diverse azithromycin resistance genes were detected in E. coli and Salmonella from food-producing animals and meat in Europe. Azithromycin resistance genes mef (C)- mph (G) and erm (42) appear to be emerging primarily in porcine E. coli isolates. The identification of distinct mph (A) operon structures in susceptible and resistant isolates increases the predictive power of WGS-based methods for in silico detection of azithromycin resistance in Enterobacterales. [ABSTRACT FROM AUTHOR]

We report the discovery of a satellite-helper phage system with a novel type of dependence on a tail donor. The Acinetobacter baumannii satellite podovirus Aci01-2- Phanie (short name Phanie) uses a phage phi29-like DNA replication and packaging mode. Its linear 11,885 bp dsDNA genome bears 171 bp inverted terminal repeats (ITR). Phanie is related to phage DU-PP-III from Pectobacterium and to members of the Astrithrvirus from Salmonella enterica. Together, they form a new clade of phages with 27% to 30% identity over the whole genome. Detailed 3D protein structure prediction and mass spectrometry analyses demonstrate that Phanie encodes its capsid structural genes and genes necessary to form a short tail. However, our study reveals that Phanie virions are non-infectious unless they associate with the contractile tail of an unrelated phage, Aci01-1, to produce chimeric myoviruses. Following the coinfection of Phanie with myovirus Aci01-1, hybrid viral particles composed of Phanie capsids and Aci01-1 contractile tails are assembled together with Phanie and Aci01-1 particles. IMPORTANCE There are few reported cases of satellite-helper phage interactions but many more may be yet undiscovered. Here we describe a new mode of satellite phage dependence on a helper phage. Phanie, like phage phi29, replicates its linear dsDNA by a protein primed-mechanism and protects it inside podovirus-like particles. However, these particles are defective, requiring the acquisition of the tail from a myovirus helper for production of infectious virions. The formation of chimeras between a phi29-like podovirus and a helper contractile tail reveals an unexpected association between very different bacterial viruses. [ABSTRACT FROM AUTHOR]

The spread of antimicrobial-resistant bacteria is a significant concern, as it can lead to increased morbidity and mortality in both humans and animals. Whole-genome sequencing (WGS) is a powerful tool that can be used to conduct a comprehensive analysis of the genetic basis of antimicrobial resistance (AMR). We compared the phenotypic and genotypic AMR profiles of 97 Salmonella isolates derived from chicken and turkey diagnostic samples. We focused AMR analysis on 5 antimicrobial classes: aminoglycoside, beta-lactam, phenicol, tetracycline, and trimethoprim. The overall sensitivity and specificity of WGS in predicting phenotypic antimicrobial resistance in the Salmonella isolates were 93.4% and 99.8%, respectively. There were 16 disagreement instances, including 15 that were phenotypically resistant but genotypically susceptible; the other instance involved phenotypic susceptibility but genotypic resistance. Of the isolates examined, 67 of 97 (69%) carried at least 1 resistance gene, with 1 isolate carrying as many as 12 resistance genes. Of the 31 AMR genes analyzed, 16 were identified as aminoglycoside-resistance genes, followed by 4 beta-lactam–resistance, 3 tetracycline-resistance, 2 sulfonamide-resistance, and 1 each of fosfomycin-, quinolone-, phenicol-, trimethoprim-, bleomycin-, and colistin-resistance genes. Most of the resistance genes found were located on plasmids. [ABSTRACT FROM AUTHOR]

The ability of Salmonella species to adhere to surfaces and form biofilms, leading to persistent environmental reservoirs, might represent a direct link between environmental contamination and food processing contamination. The purpose of this study was to investigate the biofilm-forming ability of 80 multidrug-resistant (MDR) and extended-spectrum beta-lactamase (ESBL) producing Salmonella enterica serovar Infantis strains isolated from the broiler food chain production through whole genome sequencing (WGS), PCR, and morphotype association assays. Biofilm formation was quantified by testing the strains at two different temperatures, using 96-well polystyrene plates. The rough and dry colony (rdar) morphotype was assessed visually on Congo red agar (CRA) plates. Based on our results, all tested S. Infantis strains produced biofilm at 22 °C with an rdar morphotype, while at 37 °C, all the isolates tested negative, except one positive. Most isolates (58.75%) exhibited strong biofilm production, while 36.25% showed moderate production. Only 5 out of 80 (6.25%) were weak biofilm producers. WGS analysis showed the presence of the fim cluster (fimADF) and the csg cluster (csgBAC and csgDEFG), also described in S. Typhimurium, which are responsible for fimbriae production. PCR demonstrated the presence of csgD, csgB, and fimA in all 80 S. Infantis strains. To our knowledge, this is the first study comparing the effects of two different temperatures on the biofilm formation capacity of ESBL producing S. Infantis from the broiler production chain. This study highlights that the initial biofilm components, such as curli and cellulose, are specifically expressed at lower temperatures. It is important to emphasize that within the broiler farm, the environmental temperature ranges between 18–22 °C, which is the optimum temperature for in vitro biofilm formation by Salmonella spp. This temperature range facilitates the expression of biofilm-associated genes, contributing to the persistence of S. Infantis in the environment. This complicates biosecurity measures and makes disinfection protocols on the farm and in the production chain more difficult, posing serious public health concerns. [ABSTRACT FROM AUTHOR]

In the present study, a total of 720 samples were collected from retail raw meat from 13 upazilas in Sylhet District, Bangladesh, of which 225 samples were from cattle meat, 210 samples were from goat meat, and 285 samples were from chicken meat. Salmonella enterica serovars Typhimurium and Enteritidis were screened for extended-spectrum β-lactamase (ESBL) genes using multiplex PCR. Among the 720 samples, Salmonella spp. was detected in 28.06% (202 out of 720) of the samples, with S. Enteritidis and S. Typhimurium were identified in 11.53% (83 out of 720) and 12.22% (88 out of 720) of the samples, respectively. It was found that all Salmonella enterica serovars isolated from cattle meat displayed multidrug resistance (MDR) based on antimicrobial susceptibility testing. Notably, a significant proportion of S. Enteritidis isolates and all S. Typhimurium isolates from goat meat demonstrated complete resistance to multiple drugs (ampicillin, cefuroxime, and ceftazidime). Regarding chicken meat, out of 89 isolates encompassing both S. Typhimurium and S. Enteritidis, 57 isolates (64.04%) exhibited MDR. Additionally, blaCTX-M-1 exhibited the highest occurrence at 15.69% for S. Typhimurium and 7.89% for S. Enteritidis in chicken meat. Moreover, blaCTX-M-9 was only detected at 3.92% for S. Enteritidis in chicken meat. Furthermore, blaOXA had the highest prevalence rate of 19.04% for S. Enteritidis and 25.80% for S. Typhimurium in cattle meat, followed by chicken meat. These findings highlight the urgency for monitoring ESBL-producing Salmonella in retail raw meat and the need for strict measure to manage antibiotic use to prevent the spread of multidrug-resistant and ESBL-producing Salmonella strains, thereby protecting humans and reducing public health risks. [ABSTRACT FROM AUTHOR]

Outbreaks of Enterohemorrhagic Escherichia coli (EHEC), Salmonella enterica, and Listeria monocytogenes linked to fresh produce consumption pose significant food safety concerns. These pathogens can contaminate pre-harvest produce through various routes, including contaminated water. Soil physicochemical properties and flooding can influence pathogen survival in soils. We investigated survival of EHEC, S. enterica, and L. monocytogenes in soil extracts designed to represent soils with stagnant water. We hypothesized pathogen survival would be influenced by soil extract nutrient levels and the presence of native microbes. A chemical analysis revealed higher levels of total nitrogen, phosphorus, and carbon in high-nutrient soil extracts compared to low-nutrient extracts. Pathogen survival was enhanced in high-nutrient, sterile soil extracts, while the presence of native microbes reduced pathogen numbers. A microbiome analysis showed greater diversity in low-nutrient soil extracts, with distinct microbial compositions between extract types. Our findings highlight the importance of soil nutrient composition and microbial dynamics in influencing pathogen behavior. Given key soil parameters, a long short-term memory model (LSTM) effectively predicted pathogen survival. Integrating these factors can aid in developing predictive models for pathogen persistence in agricultural systems. Overall, our study contributes to understanding the complex interplay in agricultural ecosystems, facilitating informed decision-making for crop production and food safety enhancement. [ABSTRACT FROM AUTHOR]

Salmonella infection causes epidemic death in wild songbirds, with potential to spread to humans. In February 2021, public health officials in Oregon and Washington, USA, isolated a strain of Salmonella enterica serovar Typhimurium from humans and a wild songbird. Investigation by public health partners ultimately identified 30 illnesses in 12 states linked to an epidemic of Salmonella Typhimurium in songbirds. We report a multistate outbreak of human salmonellosis associated with songbirds, resulting from direct handling of sick and dead birds or indirect contact with contaminated birdfeeders. Companion animals might have contributed to the spread of Salmonella between songbirds and patients; the outbreak strain was detected in 1 ill dog, and a cat became ill after contact with a wild bird. This outbreak highlights a One Health issue where actions like regular cleaning of birdfeeders might reduce the health risk to wildlife, companion animals, and humans.

Introduction. Salmonella Kentucky sequence type ST198 is one of the epidemiologically significant non-typhoidal Salmonella clones worldwide and is characterized by the presence of highly resistant strains and the ability to adapt to different animal hosts and environmental conditions. The aim of this study was to analyze S. Kentucky strains isolated from various sources in Russia in terms of their phylogenetic position within the global diversity of the pathogen and their genetic characteristics. Materials and methods. We examined 55 strains of S. Kentucky by whole-genome sequencing, which were isolated from 2010 to 2022 from various sources (clinical strains, food, as well as from farm animals, feed and environmental samples). Whole genome sequencing was performed using Illumina platforms. Phylogenetic analysis based on nucleotide variation analysis included an additional 390 S. Kentucky strains. Results. Most of the Russian strains (n = 50) belonged to the ST198 sequence type, four strains were ST314 and one strain was ST152. Of the 50 Russian sequence-type ST198 strains, 44 belonged to the international monophyletic MDR lineage S. Kentucky ST198, and belonged to four separate sublineages, six strains occupying a basal position in relation to the MDR lineage. A total of 320 genes and mutations responsible for resistance to antimicrobial agents were identified. The most common were point mutations in the QRDR region. In most cases, Russian strains were characterized by the presence of variants of the SGI1-K genomic island. Moreover, the putative structure of SGI1 was correlated with the phylogenetic clustering of S. Kentucky sublineages. Conclusions. The results of the study made it possible to assess the population structure of Russian S. Kentucky ST198 strains on a global scale and determine the genetic determinants of antibiotic resistance, including the structure of the SGI1 genomic island.

The effect of plasma-activated water (PAW) generated with a dielectric barrier discharge diffusor (DBDD) system on microbial load and organoleptic quality of cucamelons was investigated and compared to the established sanitizer, sodium hypochlorite (NaOCl). Pathogenic serotypes of Escherichia coli, Salmonella enterica, and Listeria monocytogenes were inoculated onto the surface of cucamelons (6.5 log CFU g-1) and into the wash water (6 log CFU mL-1). PAW treatment involved 2 min in situ with water activated at 1,500 Hz and 120 V and air as the feed gas; NaOCl treatment was a wash with 100 ppm total chlorine; control treatment was a wash with tap water. PAW treatment produced a 3-log CFU g-1 reduction of pathogens on the cucamelon surface without negatively impacting quality or shelf life. NaOCl treatment reduced the pathogenic bacteria on the cucamelon surface by 3 to 4 log CFU g-1; however, this treatment also reduced fruit shelf life and quality. Both systems reduced 6-log CFU mL-1 pathogens in the wash water to below detectable limits. The critical role of superoxide anion radical (·O2-) in the antimicrobial power of DBDD-PAW was demonstrated through a Tiron scavenger assay, and chemistry modeling confirmed that ·O2- generation readily occurs in DBDD-PAW generated with the employed settings. Modeling of the physical forces produced during plasma treatment showed that bacteria likely experience strong local electric fields and polarization. We hypothesize that these physical effects synergize with reactive chemical species to produce the acute antimicrobial activity seen with the in situ PAW system. IMPORTANCE Plasma-activated water (PAW) is an emerging sanitizer in the fresh food industry, where food safety must be achieved without a thermal kill step. Here, we demonstrate PAW generated in situ to be a competitive sanitizer technology, providing a significant reduction of pathogenic and spoilage microorganisms while maintaining the quality and shelf life of the produce item. Our experimental results are supported by modeling of the plasma chemistry and applied physical forces, which show that the system can generate highly reactive ·O2- and strong electric fields that combine to produce potent antimicrobial power. In situ PAW has promise in industrial applications as it requires only low power (12 W), tap water, and air. Moreover, it does not produce toxic by-products or hazardous effluent waste, making it a sustainable solution for fresh food safety.

Background: Salmonella infections are considered the most common foodborne pathogens responsible for zoonotic infections and food poisoning in humans and animal species such as birds. Antimicrobial resistance is considered a global anxiety, because it cause human public health repercussions, as well as lead to increase in animal morbidity and death. Aim: The aims of this study are the isolation and identification of Salmonella enterica, as well as to investigate the antimicrobial susceptibility test and the molecular characteristics using PCR and sequences for isolates from chicken products (eggs, livers and minced meat) and human in the Wasit Governorate of Iraq. Methods: A total of 300 samples (150 chicken product samples including eggs, livers, and minced meat, and 150 human fecal samples) were collected from the Wasit governorate of Iraq from January to December 2022. The bacterial isolation was done according to recommendations of ISO 6579 standard and the Global Foodborne Infections Network laboratory protocol WHO 2010. Serotyping test and Antimicrobial susceptibility test (AST) were done by using 19 antibiotic agents according to the recommendations of CLSI, 2022 by using disc diffusion susceptibility test and Vitik 2 test. Finally, the suspected isolates were confirmed using the conventional polymerase chain reaction (PCR) method and sequencing for a unique rRNA gene. Results: The results showed that the isolation percentage of S. enterica in chicken products was 8.66% (12% eggs, 6% livers and 8% minced meat), while in humans it was 4.6%. Also, showed 100% of S. Typhi in human. While, in chicken eggs S. Typhi, S. Typhimurium and S. Enteritidis were 50%, 33.33% and 16.66%, respectively. Also, showed 100% of S. Typhimurium in both livers and minced meat. The AST in human isolates showed resistance to Ampicillin, Cefotaxime, Ceftazidime, Cefepime, Amikacin, Gentamicin, Ciprofloxacin, Norfloxacin, and Ceftriaxone, while no resistance to Amoxicillin, Pipracillin, Ertapenem, Imipenem, Meropenem, Fosfomycin, Nitrofurantoin, Trimethoprim, Azithromycin, and Tetracycline. In chicken products isolates were resistance with different percentages to Amikacin, Gentamicin, Tetracycline, Ciprofloxacin, Norfloxacin, Nitrofurantoin, Ampicillin, Cefotaxime, Ceftazidime, Cefepime, and Trimethoprim; while no resistance to Amoxicillin, Pipracillin, Ertapenem, Imipenem, Meropenem, Fosfomycin, Azithromycin and Ceftriaxone. Sequencing by using rRNA gene was done for four PCR products. Conclusion: This study showed the presence of genetic mutations for S. enterica which led to variations in the molecular characteristics, and antimicrobial drug resistance of S. enterica isolated from chicken products and human. [Open Vet J 2024; 14(5.000): 1117-1129]

Abstract Seasonal fluctuations influence foodborne illness transmission and affect patterns of microbial contamination of food. Previous investigations on the seasonality of Salmonella enterica prevalence in dairy products in Ethiopia have been minimal. However, such data are needed to inform strategic development of effective interventions to improve food safety, as seasonal differences may affect intervention strategies. This study was conducted to identify differences in the prevalence of Salmonella in milk and cheese samples between wet and dry seasons. A longitudinal study design was utilized with a random sampling occurring during both dry and wet seasons. A total of 448 milk and cottage cheese samples were collected from Oromia, Sidama, and Amhara regions. Samples were tested for Salmonella using the ISO 6579-1: 2008 method, followed by PCR confirmation. A chi-square test was conducted to assess the significance of differences in the prevalence of Salmonella in the samples between the two seasons. Results from this study showed a higher prevalence of Salmonella in all sample types during the dry season (P

Background and Aim: Nosocomial infections caused by Salmonella spp. are common in veterinary facilities. The early identification of high-risk patients and sources of infection is important for mitigating the spread of infections to animal patients and humans. This study investigated the occurrence of Salmonella spp. among patients at a veterinary academic hospital in South Africa. In addition, this study describes the environmental factors that contribute to the spread of Salmonella spp. in the veterinary facility. Materials and Methods: This study used a dataset of Salmonella-positive animals and environmental samples submitted to the bacteriology laboratory between 2012 and 2019. The occurrence of Salmonella isolates at the veterinary hospital was described based on source, month, season, year, and location. Proportions and 95% confidence intervals were calculated for each variable. Results: A total of 715 Salmonella isolates were recorded, of which 67.6% (483/715) came from animals and the remainder (32.4%, 232/715) came from environmental samples. The highest proportion (29.2%) of Salmonella isolates was recorded in 2016 and most isolates were reported in November (17.4%). The winter season had the lowest (14.6%) proportion of isolates reported compared to spring (31.3%), summer (27.8%), and autumn (26.4%). Salmonella Typhimurium (20.0%) was the most frequently reported serotype among the samples tested, followed by Salmonella Anatum (11.2%). Among the positive animal cases, most (86.3%) came from equine clinics. Most reported isolates differed based on animal species with S. Typhimurium being common in equines and S. Anatum in bovines. Conclusion: In this study, S. Typhimurium emerged as the predominant strain in animal and environmental samples. Equines were the most affected animals; however, Salmonella serotypes were also detected in the production animals. Environmental contamination was also a major source of Salmonella species in this study. To reduce the risk of transmission, strict infection prevention and control measures (biosecurity) must be implemented.

Abstract Standardized and thoroughly characterized genetic tools are a prerequisite for studying cellular processes to ensure the reusability and consistency of experimental results. The discovery of fluorescent proteins (FPs) represents a milestone in the development of genetic reporters for monitoring transcription or protein localization in vivo. FPs have revolutionized our understanding of cellular dynamics by enabling the real-time visualization and tracking of biological processes. Despite these advancements, challenges remain in the appropriate use of FPs, specifically regarding their proper application, protein turnover dynamics, and the undesired disruption of cellular functions. Here, we systematically compared a comprehensive set of 15 FPs and assessed their performance in vivo by focusing on key parameters, such as signal over background ratios and protein stability rates, using the Gram-negative model organism Salmonella enterica as a representative host. We evaluated four protein degradation tags in both plasmid- and genome-based systems and our findings highlight the necessity of introducing degradation tags to analyze time-sensitive cellular processes. We demonstrate that the gain of dynamics mediated by the addition of degradation tags impacts the cell-to-cell heterogeneity of plasmid-based but not genome-based reporters. Finally, we probe the applicability of FPs for protein localization studies in living cells using standard and super-resolution fluorescence microscopy. In summary, our study underscores the importance of careful FP selection and paves the way for the development of improved genetic reporters to enhance the reproducibility and reliability of fluorescence-based research in Gram-negative bacteria and beyond.

A total of 300 samples (150 chicken products samples (eggs, livers and minced meat) from different local supermarkets and 150 human fecal samples from clinical cases) were collected for isolation and identification of Salmonella enterica from Wasit Province of Iraq from January to December 2022 by using PCR assay and sequencing for three virulence factors genes (stn, avr A, and sop B). The results of isolation for S. enterica showed 4.6% (7/150) in humans, and 8.66% (13/150) in the chicken products (6/50 eggs, 3/50 livers, and 4/50 minced meat); Also showed 7/7 of S. typhi in human, while in the eggs showed 3/6 of S. typhi, 2/6 of S. typhimurium and 1/6 of S. enteritidis. Also, the results showed 3/3 and 4/4 of S. typhimurium in both livers and minced meat, respectively. The results of virulence factors recorded that the stn gene was absent in human isolates, while 10/13 in chicken products isolates, also showed in human and chicken products isolates 7/7 and 13/13, respectively, for both avr A and sop B genes. The serovare S. typhi were 10/10 carried both avr A and sop B genes, but lacked the stn gene. While S. typhimurium and S. enteritidis were 9/9 and 1/1 respectively carried stn, avr A and sop B genes. Sequencing was done for some PCR products for three virulence factors that were registered in NCBI. The nucleotide sequencing showed many nucleotide substitutions (mutations) in the sop B and avr A genes while no substitution in the stn gene.

Uncommon Salmonella Infantis variants displaying only flagellar antigens phenotypically showed identical incomplete antigenic formula but differed by molecular serotyping. Although most formed rough colonies, all shared antimicrobial resistances and the presence of usg gene with wild-type Salmonella Infantis. Moreover, they were undistinguishable wild-type Salmonella Infantis by whole-genome sequencing.

Macrolide antibiotics, pivotal in clinical therapeutics, are confronting resistance challenges mediated by enzymes like macrolide esterases, which are classified into Ere-type and the less studied Est-type. In this study, we provide the biochemical confirmation of EstX, an Est-type macrolide esterase that initially identified as unknown protein in the 1980s. EstX is capable of hydrolyzing four 16-membered ring macrolides, encompassing both veterinary (tylosin, tidipirosin, and tilmicosin) and human-use (leucomycin A5) antibiotics. It uses typical catalytic triad (Asp233-His261-Ser102) from alpha/beta hydrolase superfamily for ester bond hydrolysis. Further genomic context analysis suggests that the dissemination of estX is likely facilitated by mobile genetic elements such as integrons and transposons. The global distribution study indicates that bacteria harboring the estX gene, predominantly pathogenic species like Escherichia coli, Salmonella enterica, and Klebsiella pneumoniae, are prevalent in 74 countries across 6 continents. Additionally, the emergence timeline of the estX gene suggests its proliferation may be linked to the overuse of macrolide antibiotics. The widespread prevalence and dissemination of Est-type macrolide esterase highlight an urgent need for enhanced monitoring and in-depth research, underlining its significance as an escalating public health issue. Macrolide esterase EstX can degrade both veterinary and human-use 16-membered ring macrolides. This enzyme is widely distributed among pathogenic species and across 74 countries on 6 continents,with its dissemination likely facilitated by integrons and transposons. [ABSTRACT FROM AUTHOR]

Antimicrobial resistance (AMR) is a major public health threat, exacerbated by the ability of bacteria to rapidly disseminate antimicrobial resistance genes (ARG). Since conjugative plasmids of the incompatibility group P (IncP) are ubiquitous mobile genetic elements that often carry ARG and are broad-host-range, they are important targets to prevent the dissemination of AMR. Plasmid-dependent phages infect plasmid-carrying bacteria by recognizing components of the conjugative secretion system as receptors. We sought to isolate plasmid-dependent phages from wastewater using an avirulent strain of Salmonella enterica carrying the conjugative IncP plasmid pKJK5. Irrespective of the site, we only obtained bacteriophages belonging to the genus Alphatectivirus. Eleven isolates were sequenced, their genomes analyzed, and their host range established using S. enterica, Escherichia coli, and Pseudomonas putida carrying diverse conjugative plasmids. We confirmed that Alphatectivirus are abundant in domestic and hospital wastewater using culture-dependent and culture-independent approaches. However, these results are not consistent with their low or undetectable occurrence in metagenomes. Therefore, overall, our results emphasize the importance of performing phage isolation to uncover diversity, especially considering the potential of plasmid-dependent phages to reduce the spread of ARG carried by conjugative plasmids, and to help combat the AMR crisis. [ABSTRACT FROM AUTHOR]

Introduction: Tuberculosis, caused by Mycobacterium tuberculosis complex (MTBC), remains a global health concern in both human and animals. However, the absence of rapid, accurate, and highly sensitive detection methods to differentiate the major pathogens of MTBC, including M. tuberculosis, M. bovis, and BCG, poses a potential challenge. Methods: In this study, we have established a triplex droplet digital polymerase chain reaction (ddPCR) method employing three types of probe fluorophores, with targets M. tuberculosis (targeting CFP-10-ESAT-6 gene of RD1 and Rv0222 genes of RD4), M. bovis (targeting CFP-10-ESATs-6 gene of RD1), and BCG (targeting Rv3871 and Rv3879c genes of 1RD1), respectively. Results: Based on optimization of annealing temperature, sensitivity and repeatability, this method demonstrates a lower limit of detection (LOD) as 3.08 copies/reaction for M. tuberculosis, 4.47 copies/reaction for M. bovis and 3.59 copies/reaction for BCG, without cross-reaction to Mannheimia haemolytica, Mycoplasma bovis, Haemophilus parasuis, Escherichia coli, Pasteurella multocida, Ochrobactrum anthropi, Salmonella choleraesuis, Brucella melitensis, and Staphylococcus aureus, and showed repeatability with coefficients of variation (CV) lower than 10%. The method exhibits strong milk sample tolerance, the LOD of detecting in spike milk was 5 × 10³ CFU/mL, which sensitivity is ten times higher than the triplex qPCR. 60 clinical DNA samples, including 20 milk, 20 tissue and 20 swab samples, were kept in China Animal Health and Epidemiology Center were tested by the triplex ddPCR and triplex qPCR. The triplex ddPCR presented a higher sensitivity (11.67%, 7/60) than that of the triplex qPCR method (8.33%, 5/60). The positive rates of M. tuberculosis, M. bovis, and BCG were 1.67, 10, and 0% by triplex ddPCR, and 1.67, 6.67, and 0% by triplex qPCR, with coincidence rates of 100, 96.7, and 100%, respectively. Discussion: Our data demonstrate that the established triplex ddPCR method is a sensitive, specific and rapid method for differentiation and identification of M. tuberculosis, M. bovis, and BCG. [ABSTRACT FROM AUTHOR]

Salmonella enterica Serovar Typhimurium (Salmonella) and its bacteriophage P22 are a model system for the study of horizontal gene transfer by generalized transduction. Typically, the P22 DNA packaging machinery initiates packaging when a short sequence of DNA, known as the pac site, is recognized on the P22 genome. However, sequences similar to the pac site in the host genome, called pseudo-pac sites, lead to erroneous packaging and subsequent generalized transduction of Salmonella DNA. While the general genomic locations of the Salmonella pseudo-pac sites are known, the sequences themselves have not been determined. We used visualization of P22 sequencing reads mapped to host Salmonella genomes to define regions of generalized transduction initiation and the likely locations of pseudo-pac sites. We searched each genome region for the sequence with the highest similarity to the P22 pac site and aligned the resulting sequences. We built a regular expression (sequence match pattern) from the alignment and used it to search the genomes of two P22-susceptible Salmonella strains—LT2 and 14028S—for sequence matches. The final regular expression successfully identified pseudo-pac sites in both LT2 and 14028S that correspond with generalized transduction initiation sites in mapped read coverages. The pseudo-pac site sequences identified in this study can be used to predict locations of generalized transduction in other P22-susceptible hosts or to initiate generalized transduction at specific locations in P22-susceptible hosts with genetic engineering. Furthermore, the bioinformatics approach used to identify the Salmonella pseudo-pac sites in this study could be applied to other phage—host systems. Author summary: Bacteriophage P22 has been a genetic tool and a key model for the study of generalized transduction in Salmonella since the 1950s, yet certain components of the generalized transduction molecular mechanism remain unknown. Specifically, the locations and sequences of pseudo-pac sites, hypothesized to facilitate packaging of Salmonella DNA by P22, have not been determined to date. In this study, we identified the specific locations and sequences of the pseudo-pac sites frequently recognized by P22 in Salmonella genomes. The identification of highly efficient pseudo-pac sites in Salmonella helps us understand the sequence specificity necessary for P22 pac site recognition and paves the way for more targeted use of generalized transduction with P22. [ABSTRACT FROM AUTHOR]

Background: Salmonella, an important foodborne pathogen, was estimated to be responsible for 95.1 million cases and 50,771 deaths worldwide. Sixteen serovars were responsible for approximately 80% of Salmonella infections in humans in China, and infections caused by a few uncommon serovars have been reported in recent years, though not with S. Welikade. This study reports the first clinical case caused by S. Welikade in China and places Chinese S. Welikade isolates in the context of global isolates via genomic analysis. For comparison, S. Welikade isolates were also screened in the Chinese Local Surveillance System for Salmonella (CLSSS). The minimum inhibitory concentrations (MICs) of 28 antimicrobial agents were determined using the broth microdilution method. The isolates were sequenced on an Illumina platform to identify antimicrobial resistance genes, virulence genes, and phylogenetic relationships. Results: The S. Welikade isolate (Sal097) was isolated from a two-year-old boy with acute gastroenteritis in 2021. Along with the other two isolates found in CLSSS, the three Chinese isolates were susceptible to all the examined antimicrobial agents, and their sequence types (STs) were ST5123 (n = 2) and ST3774 (n = 1). Single nucleotide polymorphism (SNP)-based phylogenetic analysis revealed that global S. Welikade strains can be divided into four groups, and these three Chinese isolates were assigned to B (n = 2; Sal097 and XXB1016) and C (n = 1; XXB700). In Group B, the two Chinese ST5123 isolates were closely clustered with three UK ST5123 isolates. In Group C, the Chinese isolate was closely related to the other 12 ST3774 isolates. The number of virulence genes in the S. Welikade isolates ranged from 59 to 152. The galF gene was only present in Group A, the pipB2 gene was only absent from Group A, the avrA gene was only absent from Group B, and the allB, sseK1, sspH2, STM0287, and tlde1 were found only within Group C and D isolates. There were 15 loci unique to the Sal097 isolate. Conclusion: This study is the first to characterize and investigate clinical S. Welikade isolates in China. Responsible for a pediatric case of gastroenteritis in 2021, the clinical isolate harbored no antimicrobial resistance and belonged to phylogenetic Group B of global S. Welikade genomes. [ABSTRACT FROM AUTHOR]

Salmonella enterica serovar Typhimurium is an invasive, facultative intracellular gastrointestinal pathogen that destroys the brush border of polarized epithelial cells (PEC). The brush border is critical for the functions of PEC because it resorbs nutrients from the intestinal lumen and builds a physical barrier to infecting pathogens. The manipuation of PEC during infection by Salmonella was investigated by live-cell imaging and ultrastructural analysed of the brush border. We demonstrate that the destruction of the brush border by Salmonella significantly reduces the resorption surface of PEC along with the abrogation of endocytosis at the apical side of PEC. Both these changes in the physiology of PEC were associated with the translocation of type III secretion system effector protein SopE. Additionally, the F-actin polymerization rate at the apical side of PEC was highly altered by SopE, indicating that reduced endocytosis observed in infected PEC is related to the manipulation of F-actin polymerization mediated by SopE and, to a lesser extent, by effectors SopE2 or SipA. We further observed that in the absence of SopE, Salmonella effaced microvilli and induced reticular F-actin by bacterial accumulation during prolonged infection periods. In contrast to strains translocating SopE, strains lacking SopE did not alter resorption by PEC. Finally, we observed that after engulfment of Salmonella, ezrin was lost from the apical side of PEC and found later in early endosomes containing Salmonella. Our observations suggest that the destruction of the brush border by Salmonella may contribute to the pathogenesis of diarrhea. [ABSTRACT FROM AUTHOR]