Invasive whistling frogs (Eleutherodactylus johnstonei) act as a reservoir for antimicrobial-resistant Enterobacteriaceae in Latin America's most populous city.

Invasive species represent a significant threat to ecological balance and the maintenance of native populations. Besides, these have been associated with the emergence of pathogens of public health importance, including multidrug-resistant bacteria. This study aimed to screen and describe the antimicrobial resistance profile of clinically important Enterobacteriaceae species isolated from whistling frogs (Eleutherodactylus johnstonei), an invasive anuran species in São Paulo, Brazil. Clinically relevant Enterobacteriaceae strains (n = 35) were isolated from oral and skin swabs of 19 whistling frogs and tested for antimicrobial susceptibility and antimicrobial resistance encoding genes. Resistance to amoxicillin + clavulanate and cefoxitin were the most frequent (16.67%; 4/24), followed by cefotaxime (5.71%; 2/35), ceftriaxone (2.86%; 1/35), and tetracycline (2.86%; 1/35). Among the antimicrobial resistance genes screened, blaCTX-M group 8, blaTEM, and blaCMY were identified. The whole genome of the blaCTX-M group 8-positive E. coli strain was assessed and confirmed blaCTX-M-8 presence and phylogenetic analysis. Given the synanthropic behavior of whistling frogs, these amphibians may act as carriers of antimicrobial-resistant bacteria.