High prevalence of beta-lactam-resistant Escherichia coli in South Australian grey-headed flying fox pups (Pteropus poliocephalus)

Publication summary

Antimicrobial-resistant organisms in wildlife species are concerning for many reasons including the potential for zoonotic disease transmission between wildlife and humans and the potential development and spread of resistance to critically important antibiotics. It has been shown that many species of wildlife living in closer proximity to humans, including in captivity and in rescue/rehabilitation facilities, typically have a higher prevalence of antimicrobial-resistant Escherichia coli compared to their free-living counterparts. A previous study of a particular colony of grey-headed flying fox (GHFF; Pteropus poliocephalus) in Adelaide, a city in South Australia, characterized beta-lactam-resistant E. coli in adult fruit bats. This study, using a combination of selective culture, PCR, antimicrobial susceptibility testing, whole-genome sequencing, and phylogenetic analysis, identified and genetically characterized beta-lactam-resistant E. coli isolates in rescued GHFF pups from the same colony. Results determined the prevalence of antibiotic-resistant E. coli in GHFF pups was much higher than that found in adults.

Who this is for

• Wildlife rehabilitators
• Veterinarians, especially those who work with wildlife and/or exotic species
• Natural resource managers and those who may live/work near flying fox colonies

Key Findings

• Fecal samples were analyzed from 53 GHFF pups from the Adelaide Botanic Park (ABP) colony that were taken into care during the 2018–2019 pup season. Typically, up to several hundred orphaned, abandoned, or heat-stress-affected pups are taken into care in South Australia during GHFF pup season (approximately October to February).
• The prevalence of amoxicillin-resistant E. coli in the pups was extremely high (77.4%) compared with the low levels previously detected in adult GHFFs from the ABP colony (4.1%). The high prevalence in pups sampled at entry to care (60%) and within 24 hours of entry (75%) indicates acquisition of amoxicillin-resistant E. coli prior to entering care.
• Additional resistant E. coli strains were found in the pups that have not been identified in adult GHFFs, with 24.5% of the pups carrying amoxicillin plus clavulanic acid-resistant strains and 11.3% carrying strains resistant to first- and third-generation cephalosporins.
• All 12 E. coli strain types that were identified in this study were lineages associated with humans and/or domestic animals as determined by phylogenetic analyses.
• Overall, 50.9% of the pups carried multidrug-resistant E. coli strains, in contrast to only 0.81% of adults from the ABP colony. Importantly, the amoxicillin-resistant E. coli strains from the GHFF pups did not exhibit resistance to fluoroquinolones, fourth- and fifth-generation cephalosporins, or carbapenems, all of which are critically important antimicrobials for human and veterinary medicine.
• The study discusses several factors that may influence the high prevalence of resistant E. coli in younger animals, such as preweaning and roosting behaviors and environmental conditions. Further research is needed to examine transmission dynamics and persistence of resistant bacteria as pups are transitioned through rehabilitation in preparation for release back into the wild.
• Overall, study results indicate high transmission of anthropogenic-associated beta-lactam-resistant E. coli to GHFF pups entering care resulting in potential health risks to both GHFF pups and human caregivers. Antibiotic stewardship and biosafety measures in wildlife rehabilitation/rescue facilities are recommended to help limit potential dissemination risks to other animals, humans, and into the environment.