Molecular Characteristics of Extended-Spectrum Beta-Lactamase-Producing Strains Isolated from Diseased Captive Giant Pandas () in China.

To characterize the antimicrobial resistance and virulence of pathogenic isolated from diseased captive giant pandas. Antimicrobial susceptibility and minimum inhibitory concentration (MIC) were determined by the broth dilution method. Whole-genome sequencing was used to characterize the phylogeny, serotype, virulence, resistome, plasmids, and genetic structures of the cefotaxime (CTX)-M genes. Four extended-spectrum beta-lactamase (ESBL)-producing strains were identified and the MICs against 11 antibiotics were determined. All ESBL-producing strains were resistant to more than eight antibiotics and carried the or gene in different sizes of replicon-type plasmids (pAMSH1-IncHI2, 257 kb; pAMPD2-IncFII, 89 kb; pAMPD02-IncFIB, 129 kb; and pAMSC4-IncN, 47 kb). Distinct insertional sequences and transposases were identified up-/downstream of , including IS, IS, IS, IS, and Tn. These strains also possessed at least three virulence genes of pathogenic and originated in four different evolutionary branches. One strain carried the complete locus of the enterocyte effacement pathogenicity island, but lacked the virulence genes and , indicating atypical enteropathogenic , whereas the other strains were considered to be extraintestinal pathogenic . The emergence of ESBL-producing pathogenic strains from diseased captive giant pandas warrants greater attention. The findings of this study will help to prevent the spread of these strains among captive giant pandas as well as from wild animals to humans.