Variations in antibiotic resistance profile in Enterobacteriaceae isolatedfrom wild Australian mammals

We carried out a retrospective analysis of 946 strains of Enterobacteriacea e isolated from wild Australian mammals between 1993 and 1997. The prevalen ce of resistance to fixed concentrations of 32 antimicrobial agents was det ermined, and the respective roles that taxonomic family of the host, state of origin and bacterial species play in defining prevalence and range of re sistance were investigated. Our results demonstrated a low but widespread p revalence of antimicrobial resistance in wild isolates. Only amikacin, cipr ofloxacin, meropenem and gentamicin inhibited growth in all 946 samples. Th ere was extensive variation in the combination of antibiotics to which isol ates were resistant, and multiple antibiotic resistance was common. Geograp hical location and host group significantly influenced the antibiotic resis tance profile of an isolate, whereas bacterial species influenced both the resistance profile of an isolate and the number of antibiotics it was resis tant to. The role of these factors in determining observed antibiotic resis tance profiles suggests that any study measuring resistance in wild isolate s should include the broadest possible range of bacterial species, host spe cies and sampling locations. As such, this study provides an important new baseline for future measurements of antibiotic resistance in the Australian environment.