Evaluation of a rapid latex agglutination test for detection of group B streptococci in vaginal specimens.

A rapid latex agglutination test (Bactigen Group B Streptococcus Cervical Screen) for detection of group B streptococci in cervical-vaginal specimens was evaluated using two different slide systems, the traditional serologic slide and capillary action track (Trak) slide. Culture was used as reference method. A total of 344 cervical-vaginal specimens were tested. The group B streptococci carrier rate was found by culture to be 10.8%, 56.8% of these specimens being heavily colonized. The sensitivity and specificity of the latex agglutination test in heavily colonized specimens was 95.2% and 99.3% for the serologic and track slides respectively. The overall sensitivity, including lightly colonized specimens, was 62.2%. The positive predictive value was 92% for both slide systems, and the negative predictive value 95.4% and 95.6% for the serologic and track slides respectively. The latex agglutination test, used with either slide, provides a rapid and effective method for identification of specimens heavily colonized with group B streptococci. The track slide may provide a convenient alternative to serologic slides since it does not require rotation.

Evaluation of a commercial cytotoxicity assay for detection of Clostridium difficile toxin.

A comparative study was performed to determine the accuracy of Clostridium difficile toxin detection. A commercial cytotoxicity assay (Bartels Immunodiagnostic Supply, Bellevue, Wash.) was compared with conventional microcytotoxicity assays, using Vero and MRC-5 cells. The Bartels system was found to be essentially equivalent to conventional cytotoxicity assays currently being performed for routine C. difficile toxin detection.