Nasal colonization of Staphylococcus Spp among captive and free-ranging wallabies in South Australia

Abstract

Staphylococcal species diversity has been well studied with regard to antibiotic resistance in humans and animals of commercial or social value. However, studies of free-ranging wildlife and animals of conservation value are limited. In this study, multidrug resistant staphylococci were found exclusively in free-ranging wallabies indicating human activity and prior antibiotic exposure may not be significant contributing factors to the development of antibiotic resistance in staphylococci in animal reservoirs. Eight isolates of Staphylococcus aureus were identified; one was resistant to ampicillin, penicillin and cefotaxime, one to ampicillin and penicillin and one to oxacillin, while the remaining five isolates were susceptible to all antimicrobial agents tested. Resistance to the β-lactam antibiotic family was the most prevalent with 37% of all isolates being resistant to one or more β-lactams. Fourteen species of Staphylococcus were identified from 89 strains isolated from 98 South Australian captive and free-ranging native wallabies. Among the identified isolates, Staphylococcus delphini (18%) and Staphylococcus succinus (17%) were the dominant species with single isolates of Staphylococcus cohnii, Staphylococcus carnosus and Staphylococcus hominis. To our knowledge, this is the first to study to report the presence and diversity of commensal staphylococcal species in any member of the Macropodidae family and thus provides baseline data for future work on the prevalence and diversity of common microbial pathogens in macropods.