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We determined the prevalence and molecular characteristics of blaCTX-M-55-positive Escherichia coli (E. coli) isolated from duck–fish polyculture farms in Guangzhou, China. A total of 914 E. coli strains were isolated from 2008 duck and environmental samples (water, soil and plants) collected from four duck fish polyculture farms between 2017 and 2019. Among them, 196 strains were CTX-M-1G-positive strains by PCR, and 177 (90%) blaCTX-M-1G-producing strains were blaCTX-M-55-positive. MIC results showed that the 177 blaCTX-M-55-positive strains were highly resistant to ciprofloxacin, ceftiofur and florfenicol, with antibiotic resistance rates above 95%. Among the 177 strains, 37 strains carrying the F18:A-:B1 plasmid and 10 strains carrying the F33:A-:B- plasmid were selected for further study. Pulse field gel electrophoresis (PFGE) combined with S1-PFGE, Southern hybridization and whole-genome sequencing (WGS) analysis showed that both horizontal transfer and clonal spread contributed to dissemination of the blaCTX-M-55 gene among the E. coli. blaCTX-M-55 was located on different F18:A-:B1 plasmids with sizes between ~76 and ~173 kb. In addition, the presence of blaCTX-M-55 with other resistance genes (e.g., tetA, floR, fosA3, blaTEM, aadA5 CmlA and InuF) on the same F18:A-:B1 plasmid may result in co-selection of resistance determinants and accelerate the dissemination of blaCTX-M-55 in E. coli. In summary, the F18:A-:B1 plasmid may play an important role in the transmission of blaCTX-M-55 in E. coli, and the continuous monitoring of the prevalence and transmission mechanism of blaCTX-M-55 in duck–fish polyculture farms remains important. [ABSTRACT FROM AUTHOR]

Objectives: To determine the transmission and molecular characteristics of blaNDM-producing Escherichia coli between companion animals and their healthcare providers at veterinary clinics in Guangzhou, China.Methods: A total of 359 samples from companion animals and their healthcare providers were collected at 14 veterinary clinics in Guangzhou, China. Genomic characteristics and clonal relationships for blaNDM-positive E. coli and complete plasmid sequences were characterized based on WGS data from combined Illumina and MinION platform reads.Results: Forty-five blaNDM-positive bacteria were recovered from companion animals (n = 43) and their healthcare providers (n = 2) at 10 veterinary clinics. Overall, E. coli (73.3%, 33/45) and Klebsiella pneumoniae (13.3%, 6/45) were the most prevalent species among the seven species of blaNDM-positive bacteria. Four blaNDM variants (blaNDM-1, blaNDM-4, blaNDM-5 and blaNDM-7) were identified in 45 blaNDM-positive bacteria and blaNDM-5 was the most prevalent (77.8%, 35/45). WGS indicated that the most prevalent STs were ST405 (8/33), ST453 (6/33), ST457 (6/33) and ST410 (5/33) among the 33 blaNDM-positive E. coli isolates. Phylogenomics and PFGE analysis revealed that clonal spread of blaNDM-positive ST453 E. coli isolates between companion animals and their healthcare providers was evident. In addition, two novel IncFIB plasmids carrying blaNDM-4 (pF765_FIB and pG908_FIB) were found in this study and indicated that IS26 may promote the horizontal transmission of blaNDM between different plasmid types.Conclusions: In this study we conducted a large-scale investigation on the prevalence of blaNDM-positive E. coli isolates from companion animals and their healthcare providers and revealed the clonal spread of blaNDM-positive E. coli isolates between these two groups. [ABSTRACT FROM AUTHOR]

Sewages from duck farms are often recognized as a major source of antimicrobial resistance and pathogenic bacteria discharged to natural water bodies, but few studies depicted the dynamic changes in resistome and microbial communities in the rivers under immense exposure of sewage discharge. In this study, we investigated the ecological and environmental risks of duck sewages to the rivers that geographically near to the duck farms with short-distance (<1 km) using 16S rRNA amplicon and metagenomic sequencing. The results showed that a total of 20 ARG types were identified with abundances ranged from 0.61 to 1.33 cpc. Of note, the genes modulate resistances against aminoglycoside, bacitracin and beta-lactam were the most abundant ARGs. Limnohabitans, Fluviibacter and Cyanobium were the top 3 predominant genera in the microbial community. The alpha diversity of overall microbial community decrease while the abundance of pathogen increase during the input of sewage within 200 m. Sul1 and bacA were the dominant ARGs brought from duck farm sewage. The community variations of ARGs and microbiome were primarily driven by pH and temperature. Total phosphorus was significantly correlated to alpha diversity and top 30 ARGs subtype. Stochastic processes was the dominated microbial assembly pattern and did not be altered by sewage. We also highlighted the ecological risk caused by bla GES which possibly could be mitigated by Cyanobacteria, and the natural water body can purify partial ARGs as well as microbiome from duck farms sewage. These findings expanded our knowledge regarding the ecological risks by wastes from the livestock farm, and underscoring the necessity to monitor ARGs in farm-surrounding water bodies., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Tetracycline and its derivative tigecycline are clinical options against Gram-negative bacterial infections. The emergence of mobile Tet(X) enzymes that destruct tetracycline-type antibiotics is posing a big challenge to antibacterial therapy and food/environmental securities. Here, we present an update on a growing number of Tet(X) variants. We describe structure and action of Tet(X) enzyme, and discuss the evolutional origin. In addition, potential Tet(X) inhibitors are given. This mini-review might benefit better understanding of Tet(X)-mediated tigecycline resistance. This article is categorized under: Infectious Diseases > Genetics/Genomics/Epigenetics Infectious Diseases > Environmental Factors Infectious Diseases > Molecular and Cellular Physiology., (© 2021 Wiley Periodicals LLC.)