Characterization of integron-mediated antimicrobial resistance among Escherichia coli strains isolated from a captive population of Amur tigers in China.

The present study was undertaken to identify and characterize integrons and integrated resistance gene cassettes among multidrug resistant Escherichia coli isolates from a captive population of Amur tigers (Panthera tigris altaica) in China. In addition, the prevalence of antimicrobial resistance and class I integrons was assessed in E. coli strains (n = 61) isolated from a captive population of Amur tigers in Heilongjiang Amur Tiger Park, China. Among the isolates, 52.46% (32 of 61) were positive for intI1, but no isolates carried intI2 or intI3. Most isolates were susceptible to amoxicillin/clavulanic acid, aztreonam, and polymyxin B, while they also exhibited high incidence rates of resistance to ampicillin, doxycycline, chloramphenicol, tetracycline, and dihydrofolate reductase. Sequencing analysis revealed three gene cassettes, which encoded resistance to dihydrofolate reductase (dfrA15), dihydrofolate reductase (dfrA12), and adenyltransferase (aadA2). The gene cassette arrays dfrA15 (31%) and dfrA12-aadA2 (19%) were most prevalent among these isolates.