Prevalence, resistance profile, and molecular epidemiology of extended-spectrum β-lactamases producing Escherichia coli from captive giant pandas.

Authors

Xia Yan, Lucai Wang, Huanrong Zhang, Mei Yang, Bingyu Xue, Ruoshui Zhao, Lin Li, Junjin Xie, Songrui Liu, Xueyang Fan, Xiaoyan Su

Published in

One health (Amsterdam, Netherlands). Volume 23. Pages 101513. Epub Jul 12, 2026.

Abstract

Extended-spectrum β-lactamase (ESBL)-producing Escherichia coli (E. coli), a bacterium resistant to most β-lactam antibiotics, is a critical clinical global health concern, posing significant health risks to humans and animals including giant pandas. The Chengdu Research Base of Giant Panda Breeding (CRBGP) has the world's largest captive population of giant pandas. This study aimed to investigate the prevalence, antibiotic resistance characteristics, and molecular epidemiology of ESBL-producing E. coli among captive giant pandas at the CRBGP.
ESBL production was screened in 100 E. coli isolates from 100 individual giant pandas (different ages and sexes) using the Clinical and Laboratory Standards Institute (CLSI) double-disc combination test. ESBL isolates were subjected to antimicrobial susceptibility testing of 34 antibiotics using the Kirby-Bauer disk diffusion susceptibility test (K-B). Whole genome sequencing (WGS) was performed to characterize genotypes, antibiotic resistance genes (ARGs), mobile genetic elements (MGEs), and multilocus sequence typing (MLST), and the molecular epidemiology of the isolates was further investigated using MLST and the goeBURST algorithm.
Twenty-nine ESBL-producing E. coli strains were identified (29.0%, 29/100), representing a marked increase from the 8% prevalence reported during 2020-2021. All 29 isolates exhibited high resistance to β-lactam antibiotics, with 100.0% resistance to amoxicillin, ampicillin, cefazolin, cefuroxime and cefotaxime. A total of 120 different ARG subtypes and 19 ESBL gene subtypes were detected; bla _CTX-M-4 was the most prevalent (100.0%), followed by bla _SHV-1 (96.6%), bla _CTX-M-1 and bla _CTX-M-3 (93.1% each). Analysis of MGEs revealed high carriage rates of IS26 (89.7%), intI1 (89.7%), and the conjugation-associated gene traA (51.7%). MLST identified 10 sequence types (STs) and one clonal complex (CC1), with ST132 as the founder. ST595 and ST973 were the most common STs (each n = 7).
The prevalence of ESBL-producing E. coli in captive giant pandas at the CRBGP has risen sharply (29.0%), with high-level multidrug resistance (MDR), a large ARG repertoire, and abundant MGEs indicative of strong horizontal gene transfer (HGT) potential. The presence of shared STs with other hosts suggests potential interspecies transmission. These findings underscore the urgent need for enhanced antimicrobial stewardship and continuous One Health surveillance to protect giant pandas and the broader ecosystem.

PMID:
42518600
Bibliographic data and abstract were imported from PubMed on 29 Jul 2026.

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