MICROBIAL-FLORA AND ANTIMICROBIAL SUSCEPTIBILITY PATTERNS OF ISOLATEDPATHOGENS FROM THE HORIZONTAL EAR CANAL AND MIDDLE-EAR IN DOGS WITH OTITIS-MEDIA

Objective-To compare microbial flora and antimicrobial susceptibility patterns of isolated pathogens from the horizontal ear canal and middl e ear in dogs with otitis media. Design-Prospective study. Animals-23 dogs with chronic bilateral otitis externa. Procedures-Swab specimens of the horizontal ear canal and middle ear were obtained for cytologic analysis, bacterial culture, and antimicrobial susceptibility testing , integrity of the tympanic membrane was observed. if the tympanic mem brane was intact, myringotomy was performed to collect specimens. Resu lts-Otitis media was diagnosed in 38 of 46 (82.6%) ears evaluated. The tympanic membrane was intact in 71.1% of the ears with otitis media. The 3 most common organisms isolated from the horizontal ear canal and middle ear were Staphylococcus intermedius, yeast, and Pseudomonas sp p. A difference in total isolates or susceptibility patterns between t he horizontal ear canal and middle ear was found in 34 (89.5%) ears. C ompared with results of bacterial culture, cytologic examination of sw ab specimens was not as effective for detection of rods and cocci from the middle ear. Clinical Implications-In dogs with chronic otitis ext erna, otitis media often exists even when there is an intact tympanic membrane. In our study, the same isolates were rarely found in the hor izontal ear canal and middle ear. Therefore, to choose appropriate ant imicrobial agents, in addition to cytologic examination, bacterial cul ture and susceptibility testing of swab specimens from the horizontal ear canal and middle ear should be performed.