Differences in lab results for dog skin infection bacteria

Abstract

OBJECTIVES: The aim of this study was to evaluate the reported bacteria and antibiotic sensitivities of aerobic bacterial cultures taken from the same lesion and submitted to three different laboratories. The second objective was to evaluate the clinical significance of the results. MATERIALS AND METHODS: Three cultures were collected simultaneously from the same lesion (crusts, collarettes or pustules). They were submitted to three laboratories, and the results were analysed. The cultured bacteria and reported sensitivities were compared across the laboratories. Fifteen dogs were included in the study (8 male neutered, 7 female spayed), with an age range of 2 to 17 years. RESULTS: Only 3/14 dogs had total agreement with the bacteria species grown across laboratories; however, the same staphylococcus species was grown in 12/14 dogs. Sensitivity agreement between laboratories was calculated using Cohen's kappa and Fleiss' kappa coefficient when the same bacteria were reported. There was almost perfect agreement of the sensitivity results. Four antibiotics were more likely to have disagreement: gentamicin (40%), doxycycline (26.6%), enrofloxacin (26.6%) and clindamycin (13%). CLINICAL SIGNIFICANCE: Staphylococcus species and their sensitivities were reliable and reproducible, which agree with recent studies; however, the additional bacteria reported varied considerably, which may lead to the choice of a broader spectrum antibiotic. To ensure appropriate antibiotic stewardship, all culture results should be compared to cytology results and interpreted with an understanding of the causes of canine pyoderma; any discrepancies should encourage consultation with a microbiologist.