Evaluation of the Staph-Zym system in the identification of staphylococci isolated from ovine milk and the ewe environment.

Abstract

The Staph-Zym and the Rosco Set methods were used to assign species to 142 strains of staphylococci isolated from the milk of sheep with subclinical intramammary infection or teat skin, mouth of lambs or milking machine teat cups. One hundred eleven of the same strains were also tested by Standard Laboratory Culture Media. The Rosco Set assigned species to all strains tested, but the other two methods were unable to assign species to a similar proportion of isolates. Seventy six (68.5%) of the strains tested with all three methods were not assigned the same species, each method shown a preference for particular species. The Staph-Zym and the Rosco Set identified most of the strains as members of the "epidermidis" group with the "aureus" second, while the reverse was observed with the Standard Laboratory Culture Media. Only in the case of Staphylococcus epidermidis all methods were in close agreement. When the results of the Staph-Zym and the Rosco Set are compared, although they agree on the predominant group, they disagree on the predominant species within the same group.