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Objectives: To investigate the genetic features of five plasmids recovered from an NDM-5-producing clinical Escherichia coli strain, BJ114, and to characterize the plasmid recombination event that occurred during the conjugation process.Methods: The genetic profiles of the five plasmids were determined by PCR, conjugation, S1-PFGE, Southern hybridization and WGS analysis. Plasmid sequences were analysed with various bioinformatic tools.Results: Complete sequences of five plasmids were obtained. Two small plasmids, pBJ114-141 and pBJ114-46, were speculated to have recombined into a large fusion plasmid, pBJ114T-190. When conjugated to other E. coli strains, some of the fusion plasmids were able to be resolved into the original two single plasmids. A non-conjugative plasmid, pBJ114-96, exhibited a high degree of sequence identity with the phage P7-like plasmid as well as an mcr-1-bearing plasmid. Another plasmid, pBJ114-78, was found to contain multidrug resistance genes and various mobile elements.Conclusions: The fusion plasmid recoverable from the transconjugant was found to be generated as a result of a recombination event that occurred upon interaction between a blaNDM-5-carrying plasmid and another plasmid present in the parental strain. Such recombination events presumably play a potential role in the dissemination of the blaNDM genes among different plasmids and pathogenic bacterial strains. [ABSTRACT FROM AUTHOR]

Objectives: To characterize a novel virulence-resistance plasmid pSE380T carried by a Salmonella enterica serotype Enteritidis clinical strain SE380.Methods: The plasmid pSE380T was conjugated to Escherichia coli strain J53 and sequenced by PacBio RSII, followed by subsequent annotation and genetic analysis.Results: Sequence analysis of this plasmid revealed that the entire Salmonella Enteritidis-specific virulence plasmid, pSEN, had been incorporated into an IncHI2 MDR plasmid, which comprises the cephalosporin and fosfomycin resistance determinants blaCTX-M-14 and fosA3. Based on BLAST analysis and scrutiny of insertion footprints, the insertion event was found to involve a replicative transposition process mediated by IS26, an IS element frequently detected in various resistance plasmids. The resulting pSE380T plasmid also comprises backbone elements of IncHI2 and IncFIA plasmids, producing a rare fusion product that simultaneously encodes functional features of both, i.e. virulence, resistance and high transmissibility.Conclusions: This is a novel hybrid plasmid mediating MDR and virulence from a clinical Salmonella Enteritidis strain. This plasmid is likely to be transmissible amongst various serotypes of Salmonella and other Enterobacteriaceae species, rendering a wide range of bacterial pathogens resistant to cephalosporins and fosfomycin, and further enhancing their virulence potential. It will be important to monitor the spread and further evolution of this plasmid among the Enterobacteriaceae strains. [ABSTRACT FROM AUTHOR]

Vibrio spp., known as significant marine pathogens, have become more prevalent due to global warming. Antibiotics released into the environment drive Vibrio resistance. The increasing consumption of seafood leads to more interactions between Vibrio and humans. Despite this concerning trend, there remains a lack of large-scale surveillance for Vibrio contamination across various types of food. This study isolated 4027 Vibrio strains, primarily comprising V. parahaemolyticus and V. alginolyticus , in 3581 fresh shrimp and meat products from 2013 to 2022. The Vibrio strains showed increased resistance to important antibiotics, especially β-lactams used to treat foodborne bacterial infections. Whole genome sequencing of 591 randomly chosen strains showed a strong correlation between antibiotic resistance and genotypes in Vibrio. Notably, various ESBL genes have evolved over the past 8 years, with bla VEBs being the most dominant. Additionally, carbapenemase genes, such as bla NDM-1 , have become increasingly prevalent in recent years. Various mobile genetic elements, including IncQ and IncA/C plasmids, recoverable in Vibrio , facilitate the transmission of crucial β-lactamase genes. These data provide insights into the evolutionary traits of antimicrobial resistance in foodborne Vibrio strains over a decade. Policymakers should consider these findings when devising appropriate strategies to combat bacterial antimicrobial resistance and safeguard human health. [Display omitted] • Antibiotic-resistant Vibrio strains have notably increased in animal-derived food products. • A strong correlation exists between antibiotic resistance and genotypes in foodborne Vibrio. • Mobile genetic elements enhance the spread of antibiotic resistance genes in Vibrio. [ABSTRACT FROM AUTHOR]

• Over 220 TEM variants observed to date originated from two major mutant clones. • One began with the Gly238Ser change and the other originated with the Arg164Ser substitution. • These two first-step mutants led to stepwise alteration in enzyme structure and activity. • Dissemination of strains producing TEM-1 variants underlies the markedly increased prevalence of β-lactam resistance. The TEM-1 β-lactamase can only cleave penicillin and the first-generation cephalosporins but it has evolved to become active against second-, third- and fourth-generation drugs. Through sequence analysis of natural TEM variants and those created by mutagenesis experiments, we described two distinct evolution routes of TEM-1 that has generated over 220 enzyme variants. One began with the Gly238Ser alteration and the other originated with the Arg164Ser substitution. Further acquisition of mutations in the background of each of these two first-step mutants led to stepwise alteration in enzyme structure and hence activity, eventually producing a wide range of enzyme variants whose substrate specificities cover cephalosporins of all generations. Dissemination of strains producing TEM-1 variants generated from these two evolution routes underlies the markedly increased prevalence of bacterial resistance to β-lactams in the past few decades. This study provides insights into the evolution of hydrolysing enzymes, in particular β-lactamases. [ABSTRACT FROM AUTHOR]

This study reports a comprehensive epidemiological and genetic analysis of V. cholerae strains, specifically non-O1/non-O139 serogroups, isolated from animal-derived food samples in Guangdong province from 2015 to 2019. A total of 21 V. cholerae strains were obtained, which exhibited high resistance rates for nalidixic acid (57.14 %, 12/21), ampicillin (33.33 %, 7/21), and ciprofloxacin (19.05 %, 4/21). The quinolone resistance-related gene, qnrVC , was prevalent in 80.95 % (17/21) of the isolates. Additionally, chromosomally mediated quinolone-resistance mutations, including mutations in GyrA at position 83 (S83I) and ParC at position 85 (S85L), were detected in 47.62 % of the isolates. The combination of target mutation and qnrVC genes was shown to mediate resistance or intermediate resistance to ciprofloxacin in V. cholerae. Furthermore, an IncC-type conjugative plasmid carrying thirteen antibiotic resistance genes, including genes conferring resistance to two clinically important antibiotics, cephalosporins and fluoroquinolones, was identified in the shrimp-derived strain Vc516. While none of our food isolates harbored the toxigenic CTX- and TCP-encoding genes, they did possess genes encoding toxins such as HlyA and Autoinducer-2. Notably, some V. cholerae strains from this study exhibited a close genetic relationship with clinical strains, suggesting their potential to cause human infections. Taken together, this study provides a comprehensive view of the epidemiological features and genetic basis of antimicrobial resistance and virulence potential of V. cholerae strains isolated from food in southern China, thereby advancing our understanding of this important pathogen. • Vibrio cholerae strains have been isolated from animal-derived food samples purchased in Guangdong province, China. • 80.95 % (17/21) of the V. cholerae strains possessed quinolone resistance-related gene qnrVC , and ten of them carried both gyrA (Ser83Ile) and parC (Ser85Leu) mutations. • An IncC-type conjugative plasmid carried genes conferring resistance to two clinically important antibiotics, cephalosporins and fluoroquinolones, was identified in the shrimp-derived strain Vc516. • Non-O1/non-O139 V. cholerae strains isolated from food sources in China exhibited a higher frequency of AMR genes compared to strains from other geographical regions. [ABSTRACT FROM AUTHOR]

The escalating prevalence of multidrug-resistant (MDR) bacteria pose a significant public health threat. Understanding the genomic features and deciphering the antibiotic resistance profiles of these pathogens is crucial for development of effective surveillance and treatment strategies. In this study, we employed the R10.4.1 nanopore sequencing technology, specifically through the use of the MinION platform, to analyze eight MDR bacterial strains originating from clinical, ecological and food sources. A single 72-hour sequencing run could yield approximately 12 million reads which covered a total of 34 gigabases (Gbp). The nanopore R10.4.1 data was processed using the Flye assembler, successfully assembling the genomes of eight bacterial strains and their 18 plasmids. Notably, the assemblies generated solely from R10.4.1 nanopore data closely matched those from next-generation sequencing data. Diverse antibiotic resistance patterns and specific resistance genes in the test strains were identified. Hospital strains that exhibited multidrug resistance were found to harbor various resistance genes that encode efflux pumps and extended-spectrum β-lactamases. Environmental and food sources were found to display resistance profiles in a species-specific manner. The composition of structurally complex plasmids in the test strains could also be revealed by analysis of nanopore long reads, which also suggested evidence of horizontal transfer of plasmids between different bacterial species. These findings provide valuable insights into the genetic characteristics of MDR bacteria and demonstrating the practicality of nanopore sequencing technology for detecting of resistance elements in bacterial pathogens. [ABSTRACT FROM AUTHOR]

Antibiotic resistance is a global health issue, with Klebsiella pneumoniae (KP) posing a particular threat due to its ability to acquire resistance to multiple drug classes rapidly. OXA-232 is a carbapenemase that confers resistance to carbapenems, a class of antibiotics often used as a last resort for treating severe bacterial infections. The study reports the earliest known identification of six OXA-232-producing KP strains that were isolated in Zhejiang, China, in 2008 and 2009 within a hospital, two years prior to the first reported identification of OXA-232 in France. The four KP strains carry the OXA-232 gene and exhibit hypervirulent loci, suggesting a broader temporal and geographical spread and integration of this resistance and virulence than previously recognized with implications for public health. Global analysis of all OXA-232-bearing KP strains revealed that OXA-232-encoding plasmids are conservative, while the strains were very diverse suggesting the plasmid mediated transmission of this carbapenemase genes. Importantly, a large proportion of the OXA-232-bearing KP strains also carried virulence plasmids, in particular the recent emergence of ST15 type of KP that carried both OXA-232-encoding plasmids and hypervirulent (hv) plasmids in China since 2019, highlighting the importance of the emergence of this type of KP strains in clinical setting. The early detection and investigations of OXA-232 in these strains warrants the retrospective studies to uncover the true timeline of antibiotic resistance spread, which could provide valuable insights for shaping future strategies to tackle the global health crisis. [ABSTRACT FROM AUTHOR]

Azithromycin resistance in bacterial pathogens has increased worldwide, and Klebsiella pneumoniae (K. pneumoniae) carries a variety of azithromycin resistance encoding genes. Genomic DNA of K. pneumoniae strain 16HN-12 was subjected to whole-plasmid sequencing using both the 150-bp paired-end Illumina NextSeq 500 platform and the long-read Oxford Nanopore Technologies MinION platform. Transferability of the azithromycin-resistance plasmid and the virulence plasmid was assessed by performing the conjugation assay. This study identified an IncB/O/K/Z conjugative plasmid that harboured erm (B) and mph (A) genes from a clinical K. pneumoniae strain. The plasmid was readily able to conjugate to Escherichia coli (E. coli) strain J53 and Salmonella enterica subsp. enterica serovar Typhimurium strain PY1 and promoted phenotypic resistance to azithromycin. Furthermore, the virulence plasmid harboured by this K. pneumoniae strain could be conjugated to E. coli strain EC600 and K. pneumoniae strain WZ1-2 via the help of this resistance plasmid through formation of a fusion plasmid. The fusion process was generated by homologous recombination through a homologous region located in both the virulence plasmid and resistance plasmid. Generation of this kind of conjugative plasmid simultaneously carrying virulence and resistance determinants could accelerate dissemination of these determinants and generate bacterial pathogens encoding these phenotypes. These data provide more information about transmission of azithromycin resistance and virulence determinants and call for action to further investigate and prevent such an evolutionary trend. [ABSTRACT FROM AUTHOR]