Evaluation of the Rapid ID 32 Strep system

To evaluate the performance of the Rapid ID 32 Strep system in the hands of clinical microbiologists without expert knowledge of streptococci or enterococci. One hundred and twenty-two strains of streptococci and enterococci conventionally identified in a reference laboratory were sent under code numbers to a clinical microbiology laboratory and identified with the Rapid ID 32 Strep system. Regardless of whether automatic reading and identification or visual reading with identification using tables were done, 75–77% of the 122 examined strains were correctly identified, 7% were misidentified and 16–18% could not be identified with certainty to the species level. The system correctly identified the majority of the examined pyogenic streptococci and enterococci, but only two-thirds of the viridans streptococcal strains. In a routine laboratory, the Rapid ID 32 Strep system can be used to give a rapid preliminary identification of streptococci and enterococci, but with viridans streptococci one would have to accept a certain risk of misidentification. The assay can, however, be used to biotype viridans streptococci in order to attempt to establish identity between separate isolates, e.g. from blood in patients suspected of having endocarditis.