Associação dos aspectos clínicos, citológicos e microbiológicos de otites externas crônicas em cães

Abstract

Otitis externa is characterized by inflammation of the external ear canal, which extends from the auricular pinnae to the tympanic membrane and may or may not be associated with an infection. It is the most common ear condition in dogs and affects 10% to 20% of the canine population. Cytology is frequently used for demonstrating the presence of microorganisms such as yeast and bacteria beyond the presence of biofilm. Inflamed ears, regardless of severity, tend to have a lower diversity of microorganisms, with a predominance of Staphylococcus bacteria. The objective of this study was to evaluate patients with chronic otitis externa, seeking to associate clinical and cytological analysis aspects with the isolation of Staphylococcus species and their ability to form biofilm. A total of 44 ears with chronic otitis externa were evaluated. Clinical evaluation of the ears was performed using the modified OTIS3 scale, along with the classification of the type of otitis, and samples were collected for cytological analysis and culture. The presence of microorganisms was identified and assessed, as well as the presence or absence of biofilm in citology. Cultures were performed to isolate Staphylococcus spp., identify them using MALDI-TOF, and assess biofilm formation and intensity using microtiter plates. The average duration of otitis externa cases showed no relationship with the classification of otitis or the presence of biofilm, indicating that the duration of the condition is not a determining factor in the state of the ears. A higher prevalence of mixed-breed dogs was observed, representing 40,91% (9/22). Cocci was present in 100% (44/44) of cytological analysis. Biofilm was identified in 36,36% (16/44) of slides, and the presence of exudate, pain, and odor was associated with it. Also, the identification of coccoid bacteria in high amounts with the presence of inflammatory cells. Cytological analysis revealed a low prevalence of biofilm, indicating that the chronic nature of the condition is not the only factor for its presence. Ears with greater severity and potentially irreversible changes are more likely to present with biofilm. Staphylococcus spp. was isolated from 59% (26/44) of the samples, encompassing various species, with S. pseudintermedius identified at a low prevalence and S. felis identified for the first time in a dog's ear.