Evaluation of the API 20 STREP system for species identification of streptococci associated with infective endocarditis.

A rapid commercial system (API 20 STREP gallery, API System, France) for the identification of streptococci was compared with conventional biochemical or serological methods. 77 clinical isolates from patients with infective endocarditis and six reference strains were tested. Biochemical tests showing differences between conventional methods and the API gallery were the acidification of inulin and the Voges-Proskauer reaction, but these differences did not affect the final identification of any strain. 75 strains were identified by the API system and 70 by conventional methods. 69 strains (25 groupable and 44 of 51 non-groupable streptococci) were given the same identity by both methods. One S. morbillorum was only identified by the conventional method. Seven S. sanguis I strains were identified only by the API system and confirmed by additional biochemical tests. The API gallery is a useful method for identifying streptococci associated with infective endocarditis, agreeing with conventional methods in 90% of strains. Results are usually available in 24 h.