Isolation of bacterial skin flora of healthy sheep, with comparison between frequent and minimal human handling.

Background: Few data are available regarding skin bacterial flora of healthy sheep and meticillin-resistant Staphylococcus carriage.

Hypothesis/objectives: To compare skin, ear and mucosal bacterial populations between minimally and frequently handled sheep; to determine whether the frequency of meticillin-resistant Staphylococcus aureus varied between groups.

Animals: One hundred and three healthy feedlot and show sheep from eight farms.

Methods: Swabs were collected from the dorsum, right ear and right nostril of each sheep. Two groups from each farm were evaluated, except from one farm, which had only one group. Bacterial isolates were identified to the genus or species level using phenotypic analysis or matrix-associated laser desorption/ionization time-of-flight mass spectrometry. Antimicrobial susceptibility testing and spa typing were performed on isolates of S. aureus.

Results: Sixteen bacterial genera were identified and 11 staphylococcal species, including S. aureus. The skin and mucosal bacterial flora were compared between the groups. The only statistically significant difference in bacteria was Streptococcus spp. on the dorsum (P = 0.0088), with carriage being more common in frequently handled sheep. Antimicrobial susceptibility testing did not find meticillin-resistant S. aureus. There was no significant difference in S. aureus carriage in the ear (P = 0.33), nostril (P = 0.43) or dorsum (P = 0.053) between frequently and minimally handled sheep. The S. aureus isolates belonged to six different spa types. Three were of the ST398 lineage.

Conclusions And Clinical Importance: Sheep are a potential source of livestock-associated meticillin-sensitive Staphylococcus aureus ST398.