ORIGINAL RESEARCH article
Front. Cell. Infect. Microbiol.
Sec. Antibiotic Resistance and New Antimicrobial drugs
Volume 15 - 2025 | doi: 10.3389/fcimb.2025.1663852
Antimicrobial Resistance of Enterobacteriaceae in Rabbit Farms: An Underestimated Reservoir Harboring mcr-1.1
Provisionally accepted
- 1Zhejiang Academy of Agricultural Sciences, Hangzhou, China
- 2Zhejiang A and F University, Hangzhou, China
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The transmission of antimicrobial resistance (AMR), particularly the antimicrobial resistance gene in Enterobacteriaceae, presents a critical challenge to global public health. Sichuan province is the largest producer and consumer of rabbit meat in China. However, few studies have focused on AMR surveillance in rabbits. Therefore, we conducted systematic AMR surveillance across ten intensive rabbit farms in Sichuan province. A total of 73 Enterobacteriaceae strains were isolated and identified by MALDI-TOF, including Klebsiella pneumoniae, Salmonella enterica, Enterobacter hormaechei, and Escherichia coli. Antimicrobial susceptibility testing revealed resistance rates exceeding 60% for tetracycline, ciprofloxacin, nalidixic acid, sulfamethoxazole-trimethoprim, and ampicillin. Whole-genome sequencing and bioinformatic analysis of the Escherichia coli isolates showed that ST328, ST22, and ST29 were the primary sequence types, with O178:H7 being the predominant serotype. Remarkably, 48% (35/73) of the isolates carried the mcr-1.1 gene, and among these, 82.9% (29/35) mcr-1.1-positive isolates contained the IncI2 plasmid replicon. Conjugation experiments showed that the mcr-1.1 gene in Klebsiella pneumoniae, Salmonella enterica and Escherichia coli transferred to a recipient strain. Furthermore, the genetic environment of the mcr-1.1 gene showed that it was flanked by PAP2 and a relaxase. Comparative analysis indicated that the mcr-1.1-positive plasmid exhibited high sequence identity to plasmids from human, porcine, and bovine sources. Notably, a phylogenetic analysis based on core single nucleotide polymorphisms demonstrated that certain rabbit-derived mcr-1-positive Escherichia coli strains clustered within the same evolutionary branch as human-derived strains. These findings indicated that smaller-scale breeding operations, such as rabbit farming, could serve as underrecognized reservoirs of AMR determinants, particularly the mcr-1.1 gene, thus requiring systematic assessment.
Keywords: Rabbits, Enterobacteriaceae, mcr-1.1, Horizontal transfer, whole genome sequence, surveillance
Received: 11 Jul 2025; Accepted: 12 Sep 2025.
Copyright: © 2025 Hu, Chen, Shi, Huang, Cui, Li, Ji, Bao and Liu. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence:
Guolian Bao, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
Yan Liu, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
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