Characteristics of Extended-Spectrum Beta-Lactamase (ESBL)- Producing Escherichia coli Associated with Antimicrobial Use in captive wild animals

Antimicrobial agents are a cause of the increase in antimicrobial-resistant (AMR) bacteria. We investigated the prevalence and characteristics of extended-spectrum beta-lactamase (ESBL)-producing bacteria in captive wild animals before and after exposure to antimicrobial agents. Sixty-six fecal samples were collected from captive animals (spotted deer, Rusa deer, geese, chickens, rabbits, and guinea pigs) at the Mahasarakham University Mini Zoo in Thailand on three sampling occasions: October 2021, January 2022, and April 2022. Using MacConkey agar supplemented with cefotaxime, ESBL-producing Escherichia coli (ESBL-Ec) was isolated and subjected to antimicrobial susceptibility tests and genetic analysis. The results showed a high prevalence of ESBL-Ec in the captive wild animals, with 86.4% of the samples tested positive. After deer were exposed to antimicrobials (i.e., oxytetracycline and streptomycin), the resistance rates of tetracycline and sulfamethoxazole/trimethoprim were increased as the prevalence of ESBL-Ec was increasing. ESBL-Ec isolates from some captive animals were resistant to multiple drug classes over time. CTX-M subfamily ESBL genes were found in all isolates, with the CTX-M-1 group (i.e., CTX-M-15, CTX-M-55, and CTX-M-79 genes) being the most prevalent. In conclusion, this study found a high prevalence of ESBL-Ec in captive wild animals and observed variations in AMR profiles and ESBL gene distributions. The findings highlight the potential impacts of antimicrobial use on the emergence and spread of ESBL-producing bacteria in captive animal populations and emphasize the need for targeted interventions and management practices to mitigate this issue.