Identification and antibiotic susceptibility of bacterial isolates from dogs with otitis externa in Australia.

OBJECTIVE: To identify and quantify the five most frequently isolated significant bacterial microorganisms, and their antibiotic susceptibility, from bacterial cultures of samples taken from the ears of dogs with otitis externa.
METHODS: Bacterial culture and susceptibility testing data for ear swabs from dogs with presumed otitis externa were collated and evaluated.
RESULTS: The five most frequently isolated microorganisms were: Pseudomonas aeruginosa, Staphylococcus pseudintermedius, Proteus sp., beta-haemolytic streptococci and Escherichia coli. Susceptibility to gentamicin was very high for most isolates, whereas for polymyxin B, high levels of resistance were seen. Beta-haemolytic streptococci had high levels of resistance to all of the antibiotics tested.
CONCLUSIONS: This study provides veterinarians with Australian data to assist in cytological interpretation and initial empirical therapy of canine otitis externa.