Microbiological study of the auditory canal in dairy calves with otitis media.

ABSTRACT

Otitis media (OM) in calves, is caused by different bacteria. OM treatment requires identification of etiological agents and antibiotic sensitivity testing. The gold standard method of bacteriological study of OM is tympanocentesis, but using this technique in farm condition would be difficult. As a hypothesis, it is possible that bacteriologic examining the auditory canal can help to accelerate the bacteriological investigation of OM. This study was conducted with the aim of comparing the microbiota of the auditory canal in healthy calves and calves with OM. The present research which was a case-control study, mainly compared control group (18 swab samples from healthy and non-infected ear) with two case groups (20 swab samples from the non-affected ear and 32 swab samples from the affected ear in unilateral OM, 11 swab samples from both affected ears in bilateral OM). The results of bacteriological investigations showed three categories of bacteria including pathogens (Staphylococcus chromogenes, Corynebacterium pilosum, Corynebacterium ovis, Pseudomonas aeruginosa, Pasteurella multocida, Proteus vulgaris, Trueperella pyogenes, Klebsiella, Escherichia coli, Mycoplasma bovis), opportunists (Staphylococcus intermedius, Bacillus licheniformis) and commensals (Staphylococcus epidermidis, Corynebacterium bovis, Corynebacterium renale, Bacillus subtilis, Bacillus cereus). Based on the antibiotic sensitivity test of the isolates, enrofloxacin, florfenicol, and gentamicin were the chosen antibiotics for treatment. All affected animals were treated based on bacteriological results and antibiotic sensitivity tests. All treated animals were fully cured. Based on the results, it seems that in calves with OM, examining the microbiota of the auditory canal can be further studied as an alternative to tympanocentesis in farm conditions.