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Introduction: This study characterized Vibrio alginolyticus isolated from seafood and freshwater products in China (2020)., Methods and Results: In total, 122 (95.31%) V. alginolyticus isolates were resistant to at least 1 antibiotic category, and 2 (1.56%) isolates were resistant to at least 3 antibiotic categories and belong to multi-drug resistance (MDR) isolates. A high prevalence rate was observed to be blaCARB (98.04%) encoding beta-lactam resistance, followed by tet (97.06%) encoding tetracycline resistance and fos (4.90%) encoding resistance to fosfomycin. Among the 57 V. alginolyticus isolates, the commonest virulence genes were type III secretion system translocated gene vopD , vopB , and vcrH (54.4%, 31/57), type III secretion system regulated gene tyeA (54.39%), followed by vscI and vscF (50.88%) encoded type III secretion system inner rod protein and needle protein, respectively. Multilocus sequence typing (MLST) showed considerable genetic diversity, with 34 distinct sequence types (STs) identified among 55 isolates. ST421 ( n  = 5), ST166 ( n  = 4), ST523 ( n  = 3), ST516 ( n  = 3), and ST507 ( n  = 3) were dominant STs among 55 V. alginolyticus isolates., Discussion: These findings highlight the widespread occurrence of V. alginolyticus in both freshwater and seafood products, underscoring the critical need for vigilant monitoring of these bacteria. Such measures are essential for ensuring effective food safety management and safeguarding public health., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Sun, Yan, Yan, Li, Li, Yan, Yang, Peng, Yang, Sun, Xu, Dong and Bai.)

Salmonella , especially antimicrobial resistant strains, remains one of the leading causes of foodborne bacterial disease. Retail chicken is a major source of human salmonellosis. Here, we investigated the prevalence, antimicrobial resistance (AMR), and genomic characteristics of Salmonella in 88 out of 360 (24.4%) chilled chicken carcasses, together with 86 Salmonella from humans with diarrhea in Qingdao, China in 2020. The most common serotypes were Enteritidis and Typhimurium (including the serotype I 4,[5],12:i:-) among Salmonella from both chicken and humans. The sequence types were consistent with serotypes, with ST11, ST34 and ST19 the most dominantly identified. Resistance to nalidixic acid, ampicillin, tetracycline and chloramphenicol were the top four detected in Salmonella from both chicken and human sources. High multi-drug resistance (MDR) and resistance to third-generation cephalosporins resistance were found in Salmonella from chicken (53.4%) and humans (75.6%). In total, 149 of 174 (85.6%) Salmonella isolates could be categorized into 60 known SNP clusters, with 8 SNP clusters detected in both sources. Furthermore, high prevalence of plasmid replicons and prophages were observed among the studied isolates. A total of 79 antimicrobial resistant genes (ARGs) were found, with aac(6')-Iaa , bla TEM-1B , tet(A) , aph(6)-Id , aph(3″)-Ib , sul2 , floR and qnrS1 being the dominant ARGs. Moreover, nine CTX-M-type ESBL genes and the genes bla NMD-1 , mcr-1.1 , and mcr-9.1 were detected. The high incidence of MDR Salmonella , especially possessing lots of mobile genetic elements (MGEs) in this study posed a severe risk to food safety and public health, highlighting the importance of improving food hygiene measures to reduce the contamination and transmission of this bacterium. Overall, it is essential to continue monitoring the Salmonella serotypes, implement the necessary prevention and strategic control plans, and conduct an epidemiological surveillance system based on whole-genome sequencing., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Wang, Cui, Liu, Hu, Li, Zhou, Deng, Dong, Li and Xiao.)

Salmonella enterica serotype Indiana ( S. Indiana) in Chinese poultry meat has aroused widespread concern because of its high prevalence and strong antimicrobial resistance. In consideration of the relationship in our previous study between S. Indiana and co-resistance to ciprofloxacin and cefotaxime (CIP-CTX), which were the first-line drug which were used in Salmonella infection in clinical, the antimicrobial resistance (AMR) of 224 CIP-CTX co-resistant S. Indiana isolated from retail chicken samples in China were investigated, with the aim of characterizing the AMR profiles and related resistance mechanisms to ciprofloxacin and cefotaxime among these CIP-CTX co-resistant S. Indiana isolates, all of which showed multi-drug-resistant (MDR) phenotypes. GyrA (S83F and D87N/G) with ParC (T57S and S80R) were the dominant amino acid substitution types, with oqxA , oqxB, and aac (6')-Ib-cr identified as common plasmid-mediated quinolone resistance (PMQR)-encoding genes. Five bla CTX-M gene subtypes were identified with bla CTX-M-65 ranking at the top. Equally important, we obtained one isolate CFSA664 harboring the mcr-1 gene was ESBL producer with co-resistance to nine in ten classes of tested drugs inclduing colistin. A single circular chromosome and 3 circular plasmids were found in its genome. Among the 26 AMR genes identified, 24 were located on plasmid pCFSA664-1, including three ESBL genes, while plasmid pCFSA664-3 owning only the mcr-1 gene and sharing the same backbone structure with plasmids from Enterobacteriaceae. No insertion sequences were found near the mcr-1 gene but a relaxase-encoding gene in the flank, which could transfer into E. coli J53 at a relatively high frequency. S. Indiana in this study exhibited highly drug-resistant phenotypes, contributing to the acceleration of the dissemination and emergence of this pathogen among different sources. Surveillance and a One Health strategy are needed to limit the emergence of S. Indiana along the food chain., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Hu, He, Nguyen, Liu, Liu, Gan, Wang, Dong, Xu, Li and Fanning.)

Screening drugs and compounds to fight against Cronobacter sakazakii ( C. sakazakii ), one of the most common pathogens that can cause fatal necrotizing enterocolitis, septicema and meningitis, is still needed. We found that p -coumaric acid (pCA) has an inhibitory effect on C. sakazakii in vitro and in vivo . Proteomic changes of C. sakazakii BAA-894 exposed to pCA were studied to reveal the antibacterial mechanisms involved. A total of 1,553 proteins were identified in C. sakazakii BAA-894 by label-free proteomics analysis. Fuzzy cluster analysis showed that 33 were up-regulated, and 110 were down-regulated with pCA treatment. Gene Ontology (GO) analysis concluded that pCA caused the change of metabolic state of bacteria and generally in the state of metabolic inhibition. KEGG Enrichment Analysis (KEGG) analysis showed that pCA inhibited energy metabolism and distorted the balance of amino acid metabolism. Posttranslational modification analysis showed that pCA affected the deamidation of three proteins, including Elongation factor Tu, one of the vital proteins in bacteria. Molecular docking suggested the hydrogen bond between the pCA carboxyl group and Elongation factor Tu Asn-64 might contribute to deamidation. Overall, we found that pCA interfered with cellular energy and amino acid metabolism and promoted elongation factor Tu deamidation, suggesting that pCA can be an effective natural substitute to control C. sakazakii ., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Lu, Ji, Xue, Dong and Chen.)

Clostridium botulinum is the causative pathogen of botulism. Laboratory detection of C. botulinum is essential for clinical therapy treatment of botulism due to the difficulty in diagnosis, especially in infant botulism. The extreme toxicity of botulinum neurotoxin (BoNT) requires a sensitive detection method. Due to the detection limit of real-time quantitative PCR (q-PCR), a more sensitive detection method, micro-drop digital PCR (ddPCR) was applied in C. botulinum main serotypes A and B. The following performance criteria were evaluated by ddPCR: analytical sensitivity; repeatability; and diagnostic specificity. The limit of detection (LOD) was 0.84 and 0.88 copies/μl for BoNT A and B genes, respectively, by ddPCR with high specificity, compared to 5.04×10 2 and 6.91×10 2 copies/μl by q-PCR. It was increased 10 times compared with q-PCR in spiked stool samples. This improvement in sensitivity was especially important in clinical samples as more positive samples were detected by digital PCR compared with q-PCR. Meanwhile, enrichment time for low bacteria content samples was shortened by four hours both in serotypes A and B C. botulinum by ddPCR compared with q-PCR, which are important for laboratory diagnosis and epidemiology work., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The reviewer JH declared a shared affiliation with several of the authors, YH, CY, and XX, to the handling editor at time of review., (Copyright © 2022 Gao, Wu, Zhang, Wang, Huang, Dong, Liu, Ye, Xu and Xin.)

The mcr-1 gene mediating mobile colistin resistance in Escherichia coli was first reported in China in 2016 followed by reports among different species worldwide, especially in E. coli and Klebsiella . However, data on its transmission in Salmonella are still lacking. This study analyzed the antimicrobial resistance (AMR) profiles and the mcr-1 gene presence in 755 foodborne Salmonella from 26 provinces of mainland, China in 2016. Genomic features of two mcr-1- carrying isolates, genome sequencing, serotypes and further resistance profiles were studied. Among the 755 Salmonella tested, 72.6% were found to be resistant to at least one antimicrobial agent and 10% were defined as multi-drug resistant (MDR). Salmonella Derby CFSA231 and Salmonella Typhimurium CFSA629 were mcr-1 -harboring isolates. Both expressed an MDR phenotype and included a single circular chromosome and one plasmid. Among the 22 AMR genes identified in S . Derby CFSA231, only the mcr-1 gene was localized on the IncX4 type plasmid pCFSA231 while 20 chromosomal AMR genes, including four plasmid-mediated quinolone resistance (PMQR) genes, were mapped within a 64 kb Salmonella genomic island (SGI) like region. S . Typhimurium CFSA629 possessed 11 resistance genes including an mcr-1.19 variant and two ESBL genes. Two IS 26 -flanked composite-like transposons were identified. Additionally, 153 and 152 virulence factors were separately identified in these two isolates with secretion system and fimbrial adherence determinants as the dominant virulence classes. Our study extends our concern on mcr-1 -carrying Salmonella in regards to antimicrobial resistance and virulence factors, and highlight the importance of surveillance to mitigate dissemination of mcr -encoding genes among foodborne Salmonella ., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Hu, Nguyen, Wang, Gan, Dong, Liu, Cui, Xu, Li and Fanning.)

One mcr-1 -carrying ST34-type Salmonella Typhimurium WW012 was cultured from 3,200 ready-to-eat (RTE) pork samples in 2014 in China. Broth dilution method was applied to obtain the antimicrobial susceptibility of Salmonella Typhimurium WW012. Broth matting assays were carried out to detect transferability of this phenotype and whole-genome sequencing was performed to analyze its genomic characteristic. Thirty out of 3,200 RTE samples were positive for Salmonella and the three most frequent serotypes were identified as S . Derby ( n = 8), S . Typhimurium ( n = 6), and S . Enteritidis ( n = 6). One S . Typhimurium isolate ( S . Typhimurium WW012) cultured from RTE prepared pork was found to contain the mcr-1 gene. S . Typhimurium WW012 expressed a level of high resistance to seven different antimicrobial compounds in addition to colistin (MIC = 8 mg/L). A single plasmid, pWW012 (151,609-bp) was identified and found to be of an IncHI2/HI2A type that encoded a mcr-1 gene along with six additional antimicrobial resistance genes. Plasmid pWW012 contained an IS 30 - mcr-1 - orf - orf -IS 30 composite transposon that can be successfully transferred to Escherichia coli J53. When assessed further, the latter demonstrated considerable similarity to three plasmids pHYEC7- mcr-1 , pSCC4, and pHNSHP45-2, respectively. Furthermore, plasmid pWW012 also contained a multidrug resistance (MDR) genetic structure IS 26 - aadA2 - cmlA2 - aadA1 -IS 406 - sul3 -IS 26 - dfrA12 - aadA2 -IS 26 , which showed high similarity to two plasmids, pHNLDF400 and pHNSHP45-2, respectively. Moreover, genes mapping to the chromosome (4,991,167-bp) were found to carry 28 mutations, related to two component regulatory systems ( pmrAB, phoPQ ) leading to modifications of lipid A component of the lipopolysaccharide structure. Additionally, one mutation (D87N) in the quinolone resistance determining region (QRDR) gene of gyrA was identified in this mcr-1 harboring S . Typhimurium. In addition, various virulence factors and heavy metal resistance-encoding genes were also identified on the genome of S . Typhimurium WW012. This is the first report of the complete nucleotide sequence of mcr-1 -carrying MDR S . Typhimurium strain from RTE pork in China.