Isolation of a CTX-M-55 (ESBL)-Producing Escherichia coli Strain of the Global ST6448 Clone from a Captive Orangutan in the USA

The purpose of this study was to determine if orangutans ( Pongo spp.) living in captivity at a zoo in Wisconsin were colonized with antimicrobial-resistant bacteria and, if found, to identify underlying genetic mechanisms contributing to their resistant phenotypes. We hypothesize that since antimicrobial-resistant bacteria are so prevalent within humans, the animals could also be carriers of such strains given the daily contact between the animals and the zoo staff that care for them. To test this theory, fecal samples from two orangutans were examined for resistant bacteria by inoculation on HardyCHROM™ ESBL and HardyCHROM™ CRE agars. Isolates were identified using MALDI-TOF mass spectrometry and antimicrobial susceptibility testing was performed using a Microscan autoSCAN-4 System. An isolate was selected for additional characterization, including whole genome sequencing (WGS). Using the Type (Strain) Genome Server (TYGS) the bacterium was identified as Escherichia coli . The sequence type identified was (ST/phylogenetic group/β-lactamase): ST6448/B1/CTX-M-55.