Rapid identification of group D streptococci with the API 20S system.

The API 20S system (Analytab Products) was evaluated as a means of identifying 209 isolates of Lancefield group D streptococci to the species level. Results were compared with those from a conventional tube biochemical identification system and from serological grouping. Use of the latest 20S computerized data base allowed species identification of 97% (203 of 209) of test isolates after a 4-h incubation period and 99% (208 of 209) of test isolates if supplemental overnight biochemical tests were used to clarify the identity of five Streptococcus bovis-variant isolates. The API 20S system appears to be a convenient and accurate method for rapid, same-day species identification of group D streptococci.