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This study evaluated the middle ear microbiota and antimicrobial susceptibility patterns from strains isolated from dogs with otitis media. A total of 62 dogs obtained from Zoonoses Control Center of Fortaleza CityCeará State / Brazil were studied over a 10-month period (August/2003 to June/2004. Of the total, 46.8% (n=30) of the animals were positive for otitis media and the infection was monomicrobial in 76.6% of them. The most frequent isolated agents were coagulase-positive Staphylococci (CPS-55%) and Pseudomonas sp (10%). For S. intermedius (n=13) and S. aureus subsp aureus (n=9), respectively, the greater resistance rates were observed using penicillin G (30.76% and 44.44%), ampicillin (7.69% and 44.44%), erythromycin (23.07% and 44.44%), clindamycin (23.07% and 44.44%) and thrimethropim/sulfamethoxazol (15.38% and 33.33%). Key words: otitis media, dogs, Staphylococci, antimicrobialsIn the animal practice, otitis media is a common disease and often a frustating problem. It is difficult to diagnose with the work-up being both costly and, at times invasive. In dogs the most common cause of otitis media is an extension from otitis externa and bacterial infection is more common than yeast infections (9). Cole et al.(2) compared the results of bacteriologic cultures from middle ear and the horizontal ear canal and identical isolates were found in only 10.5% of the ears. Sometimes empiric therapy is necessary, mainly in therapeutic-centers where microbiology laboratories are not available and when the invasive diagnostic is impossible to be done, as in the majority of cases of otitis media. Although predictable patterns exist, significant variation in resistance rates between medical institutions or geographical areas have been reported. Considering the great importance of the middle ear otitis in the veterinarian clinic and the few microbiological studies, the present study had as purposes to determine the etiology of canine otitis media and to evaluate the susceptibility profile of the prevalent bacteria. The criteria for the inclusion in the study were: otoscopic abnormal or ruptured tympanic membranes, otitis externa (with erythema, ulceration of the tegument, otorrhoeae and foreign bodies). The exudates of the middle ear were obtained after ear canal ablation and lateral bulla osteotomy. A 0.5 mL of BHI was injected with a syringe in the middle ear and the aspirated material was sent to the laboratory. Total transfer time to the laboratory was no longer than two hours. The specimens were inoculated onto blood agar (BAP), MacConkey agar and Brain Heart Infusion broth (BHI) and incubated at 37ºC in aerobiosis. The sample obtained for anaerobic culture was inoculated into supplemented Brain Heart Infusion agar (with 5% of sheep blood, hemine (5 μg/mL) and menadione (1 μg/mL) -and Bacteroides Bile Esculin agar and incubated at 35-37ºC in anaerobiosis. For fungal isolation, the samples were inoculated into Sabouraud glucose agar

This study determined the species of 54 staphylococci isolates from canine otitis and their ability to produce biofilm through the Congo red agar method, confirmed by scanning electron microscopy. The most frequently identified species were S. intermedius and S. simulans. Results showed that 30% of the strains were biofilm producers.

Perfil de isolamento microbiano em cães com otite média e externa associadas