Biotypes of Staphylococcus epidermidis and Micrococcus organisms, isolated from intramammary infections, reclassified into species of the genus Staphylococcus (epidermidis, hyicus, xylosus, and sciuri).

In a previous report (5), strains of Staphylococcus epidermidis and Micrococcus isolated from bovine intramammary infections were classified by the Baird-Parker (B-P) system and by serologic typing of the proteolytic enzymes. Since then, newer methods for distinguishing the genera Staphylococcus and Micrococcus and for defining new species have been reported. By utilizing these methods, the organisms from the original study were reclassified as follows: S. epidermidis B-P subgroup II, proteinase group F strains as S. epidermidis; S. epidermidis B-P subgroup III, proteinase group B strains as Staphylococcus hyicus subsp. chromogenes (pigmented) or subsp. hyicus (nonpigmented) and proteinase groups H and BH strains that were coagulase positive and nonpigmented as subsp. hyicus; B-P Micrococcus subgroup 6, proteinase group NR strains as Staphylococcus xylosus and subgroup 6, proteinase group G strains as Staphylococcus sciuri and S. xylosus. The reclassification of the strains increased the percentage of intramammary infections attributed to staphylococci from 62%, as first reported, to at least 86%.