Specific identification of Staphylococcus aureus by Staphychrom II, a rapid chromogenic staphylocoagulase test

Abstract

We compared the performance of Staphychrom II (International Microbio, Signes, France), a rapid (2-h) chromogenic staphylocoagulase test that uses human prothrombin and protease inhibitors, with those of the reference tube coagulase test (TCT) and the latex agglutination test (LAT) Slidex Staph Plus for the rapid identification of S. aureus. Prospective evaluation with 293 fresh clinical isolates yielded sensitivities, specificities, and predictive and negative predictive values of 98.1, 100, 100, and 95.1%, respectively, for the Staphychrom II test; 98.6, 98.7, 99.6, and 96.3%, respectively, for LAT; and 97.6, 98.7, 99.5, and 93.9%, respectively, for TCT. The perfect specificity of the Staphychrom II test was confirmed by testing 193 collection strains selected because of their potential testing pitfalls. The Staphychrom II test was positive for 90% of the 215 S. aureus strains tested after only 1 h of incubation. The Staphychrom II test was as sensitive as the reference TCT and was 100% specific.