This report presents the complete genome sequence of an atypical Bacillus cereus group strain carrying anthrax virulence genes isolated in China. Based on a comparison of the reference genome sequences of each species from the B. cereus group, the strain was determined to be Bacillus tropicus.

A combined molecular strategy was developed to accurately differentiate wild-type and vaccine strains of Bacillus anthracis. This approach integrates a multiplex TaqMan qPCR assay targeting the BclA, sap, and cap genes with conventional PCR analysis of BclA fragment length polymorphism. The qPCR assay demonstrated high specificity, with no cross-reactivity against other common pathogens, and exhibited a consistent limit of detection of 2.11 × 101 copies/μL (Cq < 35) for all three targets. Excellent repeatability was confirmed, with intra- and inter-assay coefficients of variation below 1.96% and 3.06%, respectively. Validation using 19 wild-type strains revealed two distinct qPCR profiles, and all wild-type strains were conclusively differentiated from the capsule-producing Chinese vaccine strain II and the acapsular Sterne strain by their characteristic BclA amplicon sizes. Through simulation PCR validation of common global canSNP genotyping (groups A, B, and C), it is possible to distinguish between wild-type and vaccine strains in China. This integrated "multiplex qPCR-BclA length analysis" protocol provides a reliable, sensitive, and specific tool for the precise detection and differentiation of B. anthracis strains in China.IMPORTANCEAnthrax, which is caused by the bacterium B. anthracis, remains a serious zoonotic disease. Its effective surveillance relies on precise strain identification. Currently, it is challenging to rapidly and accurately distinguish wild-type strains from vaccine strains, which hinders outbreak investigation and response. This study develops a novel molecular strategy combining multiple genetic targets to solve this critical diagnostic problem. The new method provides a reliable tool for strain differentiation, directly supporting accurate source tracing and informed decision-making during anthrax outbreaks. By improving diagnostic precision, this work contributes to strengthening public and veterinary health defenses against this persistent threat.

Imipenem, a critical antibiotic for treating multidrug-resistant Pseudomonas aeruginosa , now faces severe resistance from this pathogen. This study investigates the synergistic effects and underlying mechanisms of the combination of 2’’-O-galloylhyperin with imipenem against P. aeruginosa. 2’’-O-galloylhyperin showed no significant effect on the growth curve of strain 18102011 and its transconjugant D2011, while reducing the MIC of imipenem against this strain by 4-fold (FICI ≤ 0.5, synergy). This compound upregulates the citrate synthase gene gltA , and downregulates the aconitase gene acnA , enhancing citric acid synthesis while inhibiting its dehydration to cis-aconitase acid. Citric acid chelates Fe 2+ /Fe 3+ , reducing iron bioavailability, disrupting electron transfer, and increasing intracellular ROS levels in P. aeruginosa 18102011. Additionally, 2’’-O-galloylhyperin reduces the activity of the carbapenemase KPC-2. These findings highlight its potential as an adjuvant to enhance imipenem efficacy against P. aeruginosa infections.

Imipenem, a critical antibiotic for treating multidrug-resistant Pseudomonas aeruginosa, now faces severe resistance from this pathogen. This study investigates the synergistic effects and underlying mechanisms of the combination of 2’’-O-galloylhyperin with imipenem against P. aeruginosa. 2’’-O-galloylhyperin showed no significant effect on the growth curve of strain 18102011 and its transconjugant D2011, while reducing the MIC of imipenem against this strain by 4-fold (FICI ≤ 0.5, synergy). This compound upregulates the citrate synthase gene gltA, and downregulates the aconitase gene acnA, enhancing citric acid synthesis while inhibiting its dehydration to cis-aconitase acid. Citric acid chelates Fe2+/Fe3+, reducing iron bioavailability, disrupting electron transfer, and increasing intracellular ROS levels in P. aeruginosa 18,102,011. Additionally, 2’’-O-galloylhyperin reduces the activity of the carbapenemase KPC-2. These findings highlight its potential as an adjuvant to enhance imipenem efficacy against P. aeruginosa infections.

To better protect the black-faced spoonbill and explore the transmission and public health risks of drug-resistant pathogenic bacteria carried by this rare migratory bird, 249 fecal samples were collected from the black-faced spoonbills on Shicheng Island, Zhuanghe City, Liaoning Province, China in 2017 and Escherichia coli (E. coli) were isolated and identified. The BD PhoenixTM-100 automated microbial identification system and E-test strips were used to determine the resistance phenotype and minimum inhibitory concentration (MIC) value of the isolates. Whole genome sequencing and analysis were conducted on multidrug resistant (MDR) isolates and an evolutionary tree was constructed. Seventy-four samples had E. coli isolated (29.7%), 43.2% of isolates carried an antimicrobial resistant phenotype and 21.6% isolates were considered to be MDR strains. The tetracycline resistance rate was highest (41.9%), followed by ampicillin (20.3%), chloramphenicol (18.9%) and trimethoprim/sulfamethoxazole (17.6%). The highest MIC values of ampicillin, cefazolin, cefotaxime, ciprofloxacin, levofloxacin, and chloramphenicol were eight to 32 times the cutoff point for antimicrobial resistance. Twenty-one types of resistance genes and 35 virulence-associated genes were detected in the MDR isolates and the main type of plasmid was IncFIB. The mcr-1 gene was detected for the first time in MDR E. coli isolated from the black-faced spoonbill. The astA gene was only detected in nine isolates with undetected antimicrobial resistant phenotype. Genetic diversity analysis showed that nine E. coli isolates were mainly concentrated and clustered in independent evolutionary branches in the phylogenetic tree, with serotypes of O-:H8 and the multilocus sequence typing was ST2077, which were in the same evolutionary branch as habitat domesticated animals and environmental isolates. In summary, E. coli may serve as a reservoir of resistance and virulence genes in migratory birds and may be transmitted to other species during migration, with virulent or multidrug resistant E. coli a potential threat to the rare black-faced spoonbill and to human public health.

This study investigated the interactive pathogenic characteristics of co-infection with Streptococcus equi (S. equi) and Streptococcus dysgalactiae (S. dysgalactiae) isolated from diseased foals. Integrating genomic analysis, in vitro phenotypic assays, and a murine intranasal infection model, we comparatively analyzed the biological traits and pathogenic differences between single and dual infections. Comparative genomic analysis revealed divergent virulence profiles between the two isolates, and both species harbored open pan-genomes. In vitro, the biofilm biomass of strain F1 was higher than that of all other groups. No synergistic hemolytic activity was observed in co-cultures of the two isolates. In vivo infection results indicated that streptococcal infection significantly altered the structure and abundance of pulmonary microbiota in mice. Furthermore, single and dual infections displayed strain-specific and time-dependent microbial disparities at early and late infection stages, which were associated with differential enrichment of multiple immune- and metabolism-related Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, including the Tumor Necrosis Factor (TNF) and Mitogen-Activated Protein Kinase (MAPK) signaling pathways. Notably, co-infection triggered the most severe pulmonary microbiota dysbiosis and aberrant functional pathway regulation. This study preliminarily characterized the distinct phenotypic and pathological alterations induced by dual streptococcal infection, providing experimental evidence and novel insights for further exploring the interactive features of equine streptococcal mixed infections.

Background: This study aimed to construct a recombinant Pseudomonas aeruginosa outer membrane vesicle (OMV) vector vaccine delivering pcrV and compare the immunological impacts of OMVs as carriers versus as adjuvants. Methods: The recombinant plasmid pBBRMCS5-pcrV was constructed and transformed into P. aeruginosa. Recombinant OMVs (OMVPcrV) were prepared via ultracentrifugation and characterized in terms of their morphology and particle size by means of transmission electron microscopy (TEM) and nanoparticle tracking analysis (NTA). After a biosafety evaluation, mice were intramuscularly immunized with PcrV or OMVPcrV, followed by a booster immunization on day 21. On day 42, the mice were challenged subcutaneously and intranasally with PAO1. Bacterial loads in tissues and blood, pulmonary T-cell subsets, and serum antibody levels were assessed. Results: The recombinant plasmid was successfully constructed, and Western blotting confirmed the delivery of PcrV into OMVs. TEM revealed typical spherical nanostructures, and NTA showed a median particle size of 127.4 ± 5.3 nm. Upon subcutaneous challenge, the OMV, OMVPcrV, and OMV + PcrV groups all achieved 100% protection. Both the OMVPcrV and OMV + PcrV groups exhibited increased CD4+ and CD8+ T-cell counts and higher induction levels of specific IgM, IgG1, and IgG2a antibodies. The OMVPcrV group showed superior clearance of respiratory bacterial colonization and reduced inflammatory injury compared with the PBS control group. Conclusions: The constructed vector successfully delivered the PcrV antigen, and the OMVPcrV vaccine induced effective immune responses. Compared with wild-type outer membrane vesicles (OMVs) and the strategy of directly mixing free PcrV antigen with OMVs (OMV + PcrV), the recombinant OMVPcrV vaccine exhibited superior immunoprotective efficacy in terms of bacterial clearance and tissue protection, providing experimental evidence for the development of a Pseudomonas aeruginosa vaccine.

OBJECTIVES:The usage of cephalosporins (CEFs) and the co-existence of the extended-spectrum β-lactamase gene blaCTX-M in the same host may promote the prevalence of the colistin (CST) resistance gene mcr-1. This study aims to investigate the underlying mechanisms of how the mcr-1 and blaCTX-M demonstrate significant co-occurrence in Escherichia coli (E. coli). METHODS:Conjugation assays were performed on 22 porcine-derived mcr-1-positive and blaCTX-M-positive E. coli (MCRPEC::blaCTX-M+) isolates from China to assess co-transfer potential. Whole-genome sequencing characterized the genetic localization and context of mcr-1 and blaCTX-M. Fitness cost and genetic stability were evaluated through the growth curve and antimicrobial resistance (AMR) gene stability rates measurements. Additionally, we examined mcr-1 selection during blaCTX-M co-existence under CEFs' pressure by monitoring fitness and stability variations in mcr-1. RESULTS:Successful co-transfer of mcr-1 and blaCTX-M occurred in 36% (8/22) of isolates, demonstrating co-transfer efficiency ranging from 1.3 × 10-5 to 1.5 × 10-3. Predominant plasmid combinations facilitating co-transfer were the IncI2(mcr-1) + IncI1(blaCTX-M) combination. Notably, we report the first identification of blaCTX-M-positive E. coli (CTX-M-EC) carrying dual mcr-1 copies on plasmids. The mcr-1 and blaCTX-M did not exhibit fitness costs in 63% (5/8) of transconjugants, with 88% (7/8) maintaining over 70% stable rate in 10 d. CEFs' pressure enhanced both the fitness and stability of mcr-1 in blaCTX-M co-harbouring transconjugants. CONCLUSIONS:The observed high co-transfer efficiency, high stability rates, and low fitness costs of mcr-1 and blaCTX-M across distinct plasmid types and the mcr-1 selection driven by CEFs support the co-existence of mcr-1 and blaCTX-M in E. coli hosts. Our findings support the suggestion that there is an urgent need for coordinated antibiotic stewardship targeting both drug classes to curb multidrug-resistant (MDR) bacteria spread.

Backgroud:The emergence of carbapenem-resistant Pseudomonas aeruginosa (CRPA) co-producing KPC-2 and VIM-2 has increased the healthcare threats. Results:In this study, a CRPA strain 18102011, was isolated from the bile of a burn patient in ICU of China. Its whole genome was sequenced via the PacBio platform. The molecular characteristics of the genome were analyzed to assess the genetic environment of the carbapenemase genes bla KPC-2 and bla VIM-2. Antimicrobial susceptibility, plasmid stability, bacterial growth curves, and plasmid conjugation were measured. Strain 18102011 exhibited a resistant pattern to all 23 antibiotics tested, which could be defined as a pan-drug resistant P. aeruginosa strain. Two plasmids were identified in this strain: the IncpRBL16 mega-plasmid pP2011-1 carrying bla VIM-2 and the IncP6 plasmid pP2011-2 carrying bla KPC-2. bla VIM-2 was located in the region of In2057 (a novel class 1 integron) that was inserted into pP2011-1, and the expression of the bla VIM-2 gene was increased by the PcWTGN-10 promoter located at the 5'-CS. For the bla KPC-2 gene, the core module Tn3-ISKpn27-bla KPC-ΔISKpn6 served as the bla KPC-2 platform in pP2011-2, and the expression of the bla KPC-2 gene was achieved via the P1 promoter located downstream of ISKpn27. This expression pattern resulted in MICs of 4,096 μg/mL of imipenem for both strain 18102011 and its transconjugant D2011. Both plasmids were stable in strain 18102011 and could be co-transferred to other strains. Conclusion:This study raised concerns regarding the high stability and non-inferior fitness of bla KPC-2-bla VIM-2-CRPA, shed light on its genomic characteristics, and underscored the importance of continued surveillance of CRPA.

Brucellosis is listed by the World Health Organization as one of the seven most neglected global zoonotic diseases. A live-attenuated vaccine is still the main strategy used to prevent the spread of brucellosis. In this study, we constructed a two-gene (purE and purK)-deletion vaccine in Brucella melitensis vaccine strain M5 with homologous recombination. We evaluated its safety and immunogenicity in vitro and vivo, and its immunoprotective effect against B. melitensis wild-type strain 16M infection. In vitro, strain M5-ΔpurEK induced 10.50 % lactose dehydrogenase (LDH) release, only half that induced by the vaccine strain M5 (29.92 % LDH). The ability of M5-ΔpurEK to invade macrophages also decreased gradually, with a reduction of 1.02-log. In vivo, the hepatosplenic load and hepatosplenomegaly decreased significantly over time in mice inoculated with M5-ΔpurEK (P < 0.05). It elicited anti-Brucella-specific IgG responses and triggered the secretion of γ-interferon (IFN-γ) along with a low level of interleukin-6 (IL-6). Serum samples inoculated with M5-ΔpurEK were only 20 % positive on the Rose Bengal Plate Test. Hematoxylin-eosin staining showed only slight infiltration of neutrophils in the spleens of M5-ΔpurEK-infected mice on days 14 and 42 after infection. The hepatocytes in the hepatic parenchyma were sparse and lightly stained cytoplasm, with few lymphocytes around the confluent area, which gradually returned to normal within 42 days. Like parental strain M5, strain M5-ΔpurEK conferred protection against infection with B. melitensis wild-type strain 16M. In conclusion, we have shown that the deletion of purE and purK diminishes the cytotoxic effect of vaccine strain M5 on cells and organs, while leaving the degree of protection against infection with virulent wild-type Brucella strain 16M unchanged.

Gut microbes thrive by utilising host energy and, in return, provide valuable benefits, akin to a symbiotic relationship. Here, metagenomic sequencing was performed to characterise and compare the community composition, diversity and antibiotic resistance of the gut microbiota of Relict gull (Larus relictus) and Anatidae species. Alpha diversity analysis revealed that the intestinal microbial richness of L. relictus was significantly lower than that of Anatidae, with distinct differences observed in microbial composition. Notably, the intestines of L. relictus harboured more pathogenic bacteria such as clostridium, which may contribute to the decline in their population and endangered status. A total of 117 strains of Escherichia coli were isolated, with 90.60% exhibiting full susceptibility to 21 antibiotics, while 25.3% exhibited significant biofilm formation. Comprehensive Antibiotic Resistance Database data indicated that glycopeptide resistance genes were the most prevalent type carried by migratory birds, alongside quinolone, tetracycline and lincosamide resistance genes. The abundance of resistance genes carried by migratory birds decreased over time. This metagenomic analysis provides valuable insights into the intestinal microbial composition of these wild bird species, offering important guidance for their conservation efforts, particularly for L. relictus, and contributing to our understanding of pathogen spread and antibiotic-resistant bacteria.

(1) Background: Antibiotic resistance in bacteria is an urgent global threat to public health. Migratory birds can acquire antibiotic-resistant and pathogenic bacteria from the environment or through contact with each other and spread them over long distances. The objectives of this study were to explore the relationship between migratory birds and the transmission of drug-resistant pathogenic Escherichia coli. (2) Methods: Faeces and swab samples from migratory birds were collected for isolating E. coli on the Inner Mongolia Plateau of northern China from 2018 to 2023. The resistant phenotypes and spectra of isolates were determined using a BD Phoenix 100 System. Conjugation assays were performed on extended-spectrum β-lactamase (ESBL)-producing strains, and the genomes of multidrug-resistant (MDR) and ESBL-producing isolates were sequenced and analysed. (3) Results: Overall, 179 isolates were antibiotic-resistant, with 49.7% MDR and 14.0% ESBL. Plasmids were successfully transferred from 32% of ESBL-producing strains. Genome sequencing analysis of 91 MDR E. coli strains identified 57 acquired resistance genes of 13 classes, and extraintestinal pathogenic E. coli and avian pathogenic E. coli accounted for 26.4% and 9.9%, respectively. There were 52 serotypes and 54 sequence types (STs), including ST48 (4.4%), ST69 (4.4%), ST131 (2.2%) and ST10 (2.2%). The international high-risk clonal strains ST131 and ST10 primarily carried blaCTX-M-27 and blaTEM-176. (4) Conclusions: There is a high prevalence of multidrug-resistant virulent E. coli in migratory birds on the Inner Mongolian Plateau. This indicates a risk of intercontinental transmission from migratory birds to livestock and humans.

We aimed to determine the molecular characteristics of carbapenem-resistant Pseudomonas aeruginosa strains 18081308 and 18083286, which were isolated from the urine and the sputum of two Chinese patients, respectively. Additionally, we conducted a comparative analysis between Tn6411 carrying blaIMP-1 in strain 18083286 and transposons from the same family available in GenBank. Bacterial genome sequencing was carried out on strains 18081308 and 18083286 to obtain their whole genome sequence. Average nucleotide identity (ANI) was used for their precise species identification. Serotyping and multilocus sequence typing were performed. Furthermore, the acquired drug resistance genes of these strains were identified. The carbapenem-resistant P. aeruginosa strains isolated in the present study were of sequence type ST865 and serotype O6. They all carried the same resistance genes (aacC2, tmrB, and blaIMP-1). Tn6411, a Tn7-like transposon carrying blaIMP-1, was found in strain 18083286 by single molecule real time (SMRT) sequencing. We also identified the presence of this transposon sequence in other chromosomes of P. aeruginosa and plasmids carried by Acinetobacter spp. in GenBank, indicating the necessity for heightening attention to the potential transferability of this transposon.

In this report, we present the complete genome sequences of two Bacillus anthracis strains utilized as veterinary vaccines in China. The sequencing was conducted using a hybrid assembly methodology that combined Illumina short reads and PacBio long reads. This approach provides a high-quality representative sequence for the strains mentioned above.

In this study, highly carbapenem-resistant Pseudomonas aeruginosa (h-CRPA) 18102011 [the minimum inhibitory concentration (MIC) value of carbapenem antimicrobial imipenem (IP) for h-CRPA is 4,096 μg/mL] was isolated from the bile of an intensive care unit (ICU) burn patient in China, and genomic sequencing revealed a complete genome. The genome’s molecular characteristics were analyzed to assess the genetic environment of bla KPC-2 and bla VIM-2. Average nucleotide identity (ANI) comparisons were used for precise species-level identification, while serotyping, multi-locus sequence typing, and the identification of acquired resistance genes, and virulence genes were also carried out. The h-CRPA 18102011 strain carrying bla KPC-2 and bla VIM-2 was identified as strain ST2374 and the O4 serotype. Virulence genes ( plcH , exoST ) and resistance genes ( aph(3’)-IIb , aac(6’)-Ib-cr , ant(2’’)-Ia , bla OXA-396, bla PAO, bla KPC-2, bla VIM-2, bla PER-1, sul1 , catB7 , qnrVC6 , fosA ) were both identified in the genome. In addition, the IncpRBL16 type mega-plasmid pP2011-1 carrying bla VIM-2 and the IncP6 type plasmid pP2011-2 carrying bla KPC-2 were identified in the strain. The genetic environment of bla VIM-2 and bla KPC-2 was specifically evaluated to assess their origins. bla VIM-2 was located in the region of In2075 (a novel type 1 integron) that was inserted into plasmid pP2011-1, this plasmid contained 3 novel recombination sites, as well as the typical recombination site 2 ( umuC ) observed for IncpRBL16 type plasmids. However, the core module Tn 3 -IS Kpn27 - bla KPC-ΔIS Kpn6 was identified as the bla KPC-2 platform in plasmid pP2011-2. Conjugation experiments revealed that the plasmids pP2011-1 and pP2011-2 of the h-CRPA 18102011 strain could be transferred into Escherichia coli with a conjugation transfer efficiency of 10-6. The E. coli transconjugant carried bla KPC-2 and bla VIM-2 from the donor and the MIC value of IP to the E. coli transconjugant was 4,096 μg/mL, which was the same as observed for the donor. Overall, this study revealed the molecular characteristics of a VIM-2 and KPC-2-co-producing strain that was typed as O4 and ST2374. The continuous monitoring of bacteria, such as the strain investigated here, that co-harbor different types of carbapenemase genes is critical for preventing the spread of these genes.

The presence of V. parahaemolyticus in migratory birds' fecal samples implies that the human pathogenic V. parahaemolyticus strains may also potentially infect birds and thus pose a risk for zoonotic infection and food safety associated with re-entry into the environment. Our study firstly highlights the extra copy of tRNA as a potentially informative marker for identifying the bird-carried V. parahaemolyticus strains.

Background Carbapenem-resistant Klebsiella pneumoniae (CRKP) infection is a serious problem in hospitals worldwide. We monitored a tertiary hospital in Changchun, Jilin Province, China, and found that CRKP was the major species among the carbapenem-resistant isolates in sewage. Subsequently, we evaluated the drug susceptibility, resistance genes, virulence genes, outer pore membrane protein-related genes (OmpK35 & OmpK 36), multi-locus sequence typing and replicons, biofilm formation capabilities, and resistance to chlorine-containing disinfectants among KP isolates. Identification of drug sensitivity, multiple resistance profiles were observed including 77 (82.80%) multidrug resistant (MDR), 16 (17.20%) extensive drug resistant (XDR). Some antibiotic resistance genes were detected, the most prevalent carbapenemase gene was blaKPC, and 16 resistance genes were associated with other antibiotics. In addition, 3 (3.23%) CRKP isolates demonstrated loss of OmpK-35 and 2 (2.15%) demonstrated loss of OmpK-36. In the detection of multi-locus sequence typing (MLST), 11 ST11 isolates carried virulence genes. The most common replicon type was IncFII. Biofilm-forming capabilities were demonstrated by 68.8% of the isolates, all of which were resistant to chlorine-containing disinfectants. The results of the study showed that antibiotic-resistant isolates, especially CRKP, could resist disinfectants in hospital wastewater, and improper treatment of hospital wastewater may lead to the spread of drug-resistant bacteria and their genes. Thus, these bacteria must be eliminated before being discharged into the municipal sewage system.

Objectives: In this study, we report the complete genome sequence of a multidrug-resistant Escherichia coli strain recovered from a fecal sample from a captive giant panda in China. Methods: Antimicrobial susceptibility testing was performed. Genomic DNA from E. coli DC71 was se-quenced using a Nanopore PromethION sequencer instrument (Oxford Nanopore Technologies, UK) and MGI High-throughput Sequencing MGISEQ-20 0 0 platforms. The clean reads were de novo assembled us-ing SPAdes v3.11. The complete genome was annotated and analyzed using multilocus sequence typing, serotyping, plasmid replicons, fimH typing, chromosomal point mutations, acquired antimicrobial resis-tance, and virulence genes with web tools available at the Center for Genomic Epidemiology. Results: The complete genome, 4 991 906 bp in length and comprising 4677 protein-coding sequences, was generated. In silico analysis revealed that E. coli DC71 belonged to the ST410-O8:H9 subclone. A carbapenem resistance gene, blaNDM-5, was located on the pDC71-2 plasmid, coproducing blaTEM-1. Many other resistance determinants encoded by chromosomes and pDC71-3 were found. The virulence related genes carried by chromosomes were mostly related to enterohemorrhagic E. coli (EHEC) O157:H7. Conclusions: To our knowledge, this is the first complete genome of an E. coli ST410-O8:H9 strain recov-ered from captive giant panda in China. This multidrug-resistant E. coli subclone may pose potential risks to human and animal health. The genome sequence will be helpful to understand the genomic structure, its diversity, and the molecular mechanism allowing bacteria to disseminate the resistance gene. (c) 2022 The Author(s). Published by Elsevier Ltd on behalf of International Society for Antimicrobial Chemotherapy. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )

BackgroundWohlfahrtiimonas chitiniclastica is an emerging fly-borne zoonotic pathogen, which causes infections in immunocompromised patients and some animals. Herein, we reported a W. chitiniclastica BM-Y from a dead zebra in China.MethodsThe complete genome sequencing of BM-Y showed that this isolate carried one chromosome and one novel type of blaVEB–1-carrying plasmid. Detailed genetic dissection was applied to this plasmid to display the genetic environment of blaVEB–1.ResultsThree novel insertion sequence (IS) elements, namely ISWoch1, ISWoch2, and ISWoch3, were found in this plasmid. aadB, aacA1, and gcuG were located downstream of blaVEB–1, composing a gene cassette array blaVEB–1–aadB–aacA1–gcuG bracketed by an intact ISWoch1 and a truncated one, which was named the blaVEB–1 region. The 5′-RACE experiments revealed that the transcription start site of the blaVEB–1 region was located in the intact ISWoch1 and this IS provided a strong promoter for the blaVEB–1 region.ConclusionThe spread of the blaVEB–1-carrying plasmid might enhance the ability of W. chitiniclastica to survive under drug selection pressure and aggravate the difficulty in treating infections caused by blaVEB–1-carrying W. chitiniclastica. To the best of our knowledge, this is the first report of the genetic characterization of a novel blaVEB–1-carrying plasmid with new ISs from W. chitiniclastica.

This study aimed to characterize the antimicrobial resistance and virulence of Enterococcus from dogs and cats in Northeast China and evaluate its zoonotic risk based on a total of 469 enterococci strains from 610 samples, including 238 strains of E. faecium and 128 strains of E. faecalis. The isolation rate from police dog samples was 93.79%, pet dog samples was 69.90% and pet cat samples was 76.67%. The differences in the prevalence of E. faecalis among different hosts were statistically significant (P<0.05). The assays showed that most of the virulence genes detected were existed in E. faecalis and police dogs carried the least number of virulence genes. The correlation between enterococcal surface protein (esp) and aggregation substance (asa1) was determined. Enterococci are most resistant to tetracycline and erythromycin, 68.92% of the isolates were classified as multiple drug resistant. Significant differences (P<0.01) were found between E. faecium and E. faecalis in the resistance rates of nine antimicrobials. Four positive and four negative correlations were found between virulence genes and antimicrobial resistance. The results show that Enterococcus colonization and excretion in dogs and cats were related to animal species and living environments. Some correlation between virulence factors and antimicrobial resistance was obtained. This study confirmed the presence of strains carrying multiple virulence factors and antimicrobial resistance at the same time, suggesting a public health risk for dogs and cats as reservoirs of enterococci.