Applications of LightCycler Staphylococcus M-GRADE assay to detect Staphylococcus aureus and coagulase-negative staphylococci in clinical blood samples and in blood culture bottles.

We evaluated the applicability of the LightCycler Staphylococcus M(GRADE0 assay on artificially infected blood samples from healthy donors and on clinical specimens of 31 hospitalized patients. The sensitivity and specificity of the assay for detecting Staphylococcus aureus was 100% in blood samples, and 100% in blood culture bottles, when data from the BACTEC 9120 blood culture system were taken as gold standard. The same specificity and sensitivity was found during the search for CoNS (Coagulase Negative Staphylococci) in blood culture bottles, whereas a 93.33% sensitivity and 100% specificity was observed for detecting CoNS directly in blood clinical specimens.