Antibiotic-resistant characteristics and horizontal gene transfer ability analysis of extended-spectrum β-lactamase-producing Escherichia coli isolated from giant pandas.

Extended-spectrum β-lactamase (ESBL)-producing Escherichia coli (ESBL-EC) is regarded as one of the most important priority pathogens within the One Health interface. However, few studies have investigated the occurrence of ESBL-EC in giant pandas, along with their antibiotic-resistant characteristics and horizontal gene transfer abilities. In this study, we successfully identified 12 ESBL-EC strains (8.33%, 12/144) out of 144 E. coli strains which isolated from giant pandas. We further detected antibiotic resistance genes (ARGs), virulence-associated genes (VAGs) and mobile genetic elements (MGEs) among the 12 ESBL-EC strains, and the results showed that 13 ARGs and 11 VAGs were detected, of which bla _CTX-M (100.00%, 12/12, with 5 variants observed) and papA (83.33%, 10/12) were the most prevalent, respectively. And ISEcp1 (66.67%, 8/12) and IS26 (66.67%, 8/12) were the predominant MGEs. Furthermore, horizontal gene transfer ability analysis of the 12 ESBL-EC showed that all bla _CTX-M genes could be transferred by conjugative plasmids, indicating high horizontal gene transfer ability. In addition, ARGs of rmtB and sul2 , VAGs of papA , fimC and ompT , MGEs of ISEcp1 and IS26 were all found to be co-transferred with bla _CTX-M . Phylogenetic analysis clustered these ESBL-EC strains into group B2 (75.00%, 9/12), D (16.67%, 2/12), and B1 (8.33%, 1/12), and 10 sequence types (STs) were identified among 12 ESBL-EC (including ST48, ST127, ST206, ST354, ST648, ST1706, and four new STs). Our present study showed that ESBL-EC strains from captive giant pandas are reservoirs of ARGs, VAGs and MGEs that can co-transfer with bla _CTX-M via plasmids. Transmissible ESBL-EC strains with high diversity of resistance and virulence elements are a potential threat to humans, animals and surrounding environment.
Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
(Copyright © 2024 Liu, Fan, Zhang, Yuan, Zhong, Wang, Wang, Zhou, Zhang, Geng, Peng, Wang, Zhang, Yan, Luo, Shi and Zhong.)