RAPID IDENTIFICATION OF STAPHYLOCOCCUS-AUREUS FROM BLOOD CULTURE BOTTLES BY A CLASSIC 2-HOUR TUBE COAGULASE TEST

The rapid, reliable identification of Staphylococcus aureus from posit ive blood cultures provides important information, While multiple meth odologies for detection of S. aureus from blood culture broths exist, none is satisfactory, Immunologic tests have shown varied sensitivitie s, the thermonuclease test, while sensitive, is not practical for rout ine use, and probe tests are expensive, Few studies have addressed usi ng the tube coagulase test (TCT), This study compared two immunologic methods, the Staph Latex kit (Remel Laboratories) and the Staphaurex k it (Wellcome Diagnostics), with a rabbit plasma TCT (Difco Laboratorie s) to identify S. aureus within 2 h directly from blood culture broths and pelleted supernatants from BACTEC (Johnston Laboratories) bottles , One hundred twelve unique clinical blood culture isolates consistent with a Gram stain for staphylococci and 68 negative blood culture bot tles seeded with a variety of gram-positive organisms were evaluated, Sensitivity and specificity among clinical specimens for the 2-h TCT w ere 79.5 and 100%, respectively, Sensitivities for the immunologic met hods were 12.8 and 10.2% for the Staphaurex and Remel Staph Latex, res pectively, and specificities for both were 100%, These results contrad ict previously reported results for both immunologic and TCT methods a nd dictate that a specific as well as a sensitive method be employed, The 2-h TCT was found to be a cost-effective; reliable, and, rapid met hod for identifying S. aureus from positive blood cultures.