Biochemical Characteristics of Staphylococcus Species of Human and Bovine Origin ¹

Thirty-three biochemical characteristics were compared for 855 staphylococci isolated from human (93) and bovine sources (762). Differences in the predominant Staphylococcus species present and biochemical characteristics of species were observed for isolates from bovine milk and human clinical sources as well as between milk isolates obtained during the 1960s and 1980s from the same herd. All isolates were bacitracin-resistant and 98% were lysostaphin-sensitive. Approximately 31% of S. hyicus strains were coagulase-positive. Thermonuclease activity was observed for strains other than S. aureus . Milk strains were more salt tolerant than human strains. Carbohydrates tended to be utilized by a greater percentage of milk strains than human strains within a given species. Many milk isolates failed to utilize glycerol in the presence of 0.4 μg erythromycin/mL. The results of this study indicate that the source of isolates may influence the predominant species present and species biochemical characteristics. These differences in species characteristics may affect results obtained for identification of nonhuman isolates with rapid identification systems where the data bases are generally based on human clinical isolates.