Systemic antibiotic use in fire-affected koalas (Phascolarctos cinereus) admitted to two wildlife treatment facilities during the 2019-2020 wildfires.

Antimicrobial resistance (AMR) is a global health threat for people and animals, including wildlife. The overuse and misuse of antimicrobials continues to fuel the spread of AMR. We performed a retrospective analysis of systemic antibiotic administration in fire-affected koalas admitted to two wildlife treatment facilities during the catastrophic Australian wildfires in 2019-2020, to assess the practice of antimicrobial stewardship during a wildlife emergency. Triage and treatment records were obtained for fire-affected koalas (n = 355) admitted to two facilities during the wildfires. Analyses showed that 40.3% of koalas at Facility A and 35.0% of koalas at Facility B received systemic antibiotics. The majority of antibiotics (63.9%, comprising multiple types of beta-lactams) administered to koalas at Facility A were prophylactic treatments in koalas with noninfected moderate to severe cutaneous burn wounds. The majority of antibiotics (75.0%, comprising chloramphenicol and enrofloxacin) administered to koalas at Facility B were chlamydial disease treatments. Overall, 29.4% of all antibiotic treatments (predominantly beta-lactams and enrofloxacin) were administered for recorded clinical infections. Where koala-specific guidelines and protocols for treating burn wounds were not available, there was an overuse of systemic antibiotics and frequently sub-optimal antibiotic stewardship in burnt koalas during the 2019-2020 wildfire emergency response. Best practice antibiotic prescribing was also not always feasible due to a shortage of first-choice antibiotics (e.g., injectable chloramphenicol for chlamydial disease). This study highlights the importance of preparedness for future wildfire events and identifies a need for equipping veterinarians with guidelines for treating fire-affected koalas during emergency situations. Additional education, guidance and resources are required to enable appropriate antimicrobial stewardship by responding veterinarians during wildlife emergencies.