An evaluation of a rapid latex test for the diagnosis of Clostridium difficile-associated diarrhea.

We present here the results of an evaluation of a rapid latex test for detection of Cl. stridium difficile-associated in comparison with our standard cytotoxin assay and culture for C. difficile. Some 515 diarrheal stools were examined. C. difficile was cultured from 70 specimens (13.5%); 53 specimens (10.2%) were positive with the latex test, and 50 (9.6%) by cytotoxin assay. The latex test did not differ significantly from the cytotoxin assay in sensitivity or specificity compared to culture results. There was also no significant difference in the specificity of the latex test compared to cytotoxin assay in patients in whom the diagnosis of C. difficile-associated diarrhea was negative. Positive and negative predictive values of the latex test for C. difficile-associated diarrhea were similar to those of cytotoxin assay. The latex test thus appears to be a rapid and practical test for the laboratory diagnosis of C. difficile-associated diarrhea. To optimize specificity and sensitivity its use should be restricted to patients where the diagnosis is strongly suspected and a rapid answer is required. As it does not distinguish between toxigenic virulent C. difficile strains and non-toxigenic avirulent strains, it would seem prudent to confirm positive results subsequently by demonstrating in-vivo or in-vitro cytotoxin production.