New medium for isolation of Corynebacterium vaginale from genital specimens

Corynebacterium vaginale was isolated from 48 (23.4%) cervical, vaginal, and urethral swabbings of 205 female outpatients. A new medium modified from peptone starch dextrose agar was used to isolate C. vaginale from most specimens. The new medium contained starch without dextrose with brom cresol purple added. With the exception of certain strains of streptococci, C. vaginale was the only organism isolated from genital specimens that grew and fermented starch on the medium. The new medium provided a rapid means of detecting and isolating C. vaginale compared to other media, and for estimating the relative predominance of the organism in mixed culture. Gram strains were used to detect clue cells in direct smears of clinical material. These cells were detected in only 12 of 48 specimens from which C. vaginale was isolated. Smears on 8 additional specimens contained clue cells but C. vaginale was not isolated. Purple broth base was superior to cystine trypticase agar for confirmatory tests with C. vaginale.