Features of laboratory diagnostics of Corynebacterium auriscanis isolated from clinical material from dogs

A representative of the opportunistic pathogenic microflora Corynebacterium auriscanis is found in the study of biological material from dogs in monoculture and in association. Most often, this species was isolated in an ear swab from dogs with clinical signs of otitis media. We studied 12 cultures isolated in swabs from the ear, vagina, and wound washings during the development of pathological processes in them. Identification was made using classical bacteriological methods and MALDI-TOF mass spectrometry. Cultivation was carried out for two days, since after a day the corynebacteria did not show cultural and biochemical properties. On the second day on solid nutrient media, the growth of opaque, dense, rounded colonies with smooth edges was noted. The morphology of the isolated microorganism was studied in Gram smears: on the first day of cultivation, Gr+ ovoids were found collected in several cells, less often singly. On the second day, Gr+ short sticks with a club-shaped thickening at one end, located in pairs at an angle in the shape of the letter V. The isolated cultures were catalase-positive, fermented glucose under aerobic conditions, did not break down lactose, sucrose, mannitol, inositol, urea, did not have hemolytic activity. The sensitivity to antibiotics was determined by the disk diffusion method on Muller - Hinton agar. In all cases, the isolates were resistant to oxacillin with a delay zone of zero. Taking into account the studied biological properties of the pathogen, the need for differential diagnosis from representatives of the genera Staphylococcus and Bacillus was established. On the basis of this study, it is recommended that when conducting a bacteriological analysis of clinical material from dogs, cultivate crops for two days, with doubtful results of a daily culture study.