Cutaneous populations of bacteria and yeast as determined by culture and cytology in healthy and diseased guinea pigs

Objective: To describe yeast and aerobic bacterial organisms found on the skin of healthy and diseased guinea pigs using cytology and culture. Methods: For this cross-sectional study, guinea pigs were recruited over a 4-year period and were allocated into 1 of 3 groups: healthy, dermatological disease, or nondermatological illness. Aerobic bacterial and fungal culture swabs were obtained from predesignated sites. Guinea pigs with dermatological conditions had additional samples obtained from lesional skin. Acetate tape cytology samples were analyzed from all sites. Results: 46 guinea pigs were included: 16 in the healthy group, 16 in the dermatological group, and 14 in the nondermatological illness group. Staphylococcus xylosus was the most frequently identified bacterium. Aerococcus viridans was the second most frequently identified bacterium. Staphylococcus aureus was not isolated in any sites of dermatological disease. Although Malassezia yeast organisms were appreciated cytologically, none grew on culture. Dermatophytes were not identified in any guinea pigs without dermatological disease. Conclusions: S xylosus was the most frequently identified bacterium. Despite previous reports of S aureus being associated with dermatological disease in guinea pigs, it was not cultured from any lesional skin. Although no Malassezia organisms were cultured, they were present on cytology, suggesting that different testing techniques may need to be utilized for identification. Clinical Relevance: The information gained is valuable for understanding populations of yeast and bacteria identified through culture and cytology colonizing guinea pig skin.