IDENTIFICATION OF COAGULASE-NEGATIVE STAPHYLOCOCCI AND TYPING OF STAPHYLOCOCCUS-EPIDERMIDIS BY A 4-H MICROMETHOD

A new 4 h micromethod (Minibact-S) for identification of coagulase-neg ative staphylococci (CNS) important in human medicine, Staphylococcus epidermidis, Staphylococcus hominis, Staphylococcus haemolyticus and S taphylococcus saprophyticus, has been investigated. The reproducibilit y for species identification was 100% and the reproducibility for the single reactions was 95%. When compared to a modified Kloos & Schleife r conventional identification method, discrepant identification was ob tained with the Minibact-S in only 8 of 382 clinical and reference str ains. The system has been used for typing and biotyping of 201 S. epid ermidis strains, and gave a subdivision in 69 different types; 4 relat ed types accounted for 91 (45%) of the isolates, whereas 44 types were represented by only 1 isolate. The discriminatory index was 0.82. In a comparison with other typing methods performed on 81 isolates from 1 5 patients Minibact-S gave about the same number of types as antibiogr ams, but in 20% of the patients extra types were obtained with Minibac t-S alone compared to antibiogram alone and vice versa. The Minibact-S is of some value in the routine clinical microbiology laboratory as a first screening method for identification of coagulase-negative staph ylococci and typing of S. epidermidis in combination with the antibiog ram.