Further evaluation of immunofluorescence techniques for detection of Shigellae in fecal specimens.

The fluorescent antibody (FA) tests for group B and group D Shigella were reevaluated. Duplicate swab specimens from patients suspected of having shigellosis were cultured shortly after collection and after transport in a soft-agar holding medium. Smears for FA examination were made at the same time. Results obtained for the group D Shigella agree closely with those obtained in previous studies. The percentage of isolations of group B Shigella from transported specimens which were positive by FA was 59.6% as compared to 39.3 and 53.3% in previous studies. S. flexneri was isolated from 76.7% of the FA-positive specimens when they were examined shortly after collection. More isolates of Shigella were obtained when specimens were examined by both methods than when either method was used alone. The results indicated that FA tests for both group B and group D Shigella are practical and may be useful to laboratories engaged in Shigella isolation.