Analysis of latex agglutination test for Clostridium difficile toxin A (D-1) and differentiation between C difficile toxins A and B and latex reactive protein.

Virulent toxigenic and avirulent non-toxigenic strains of Clostridium difficile gave a positive result in the latex agglutination test (LAT) for C difficile toxin A (D-1). Similar concentrations of latex agglutinating antigen were produced by these strains in vivo. Positive reactions were also given by C sporogenes, proteolytic C botulinum Types A, B, and A/F, and Bacteroides assaccharolyticus. The latex agglutinating antigen was denatured by boiling for 10 minutes, but not by heating at 56 degrees C for 30 minutes. The reaction was abolished by incubation of test material with crude C difficile antitoxin but not with other clostridial antitoxins or specific antitoxin to C difficile toxin A. The latex agglutinating antigen present in C difficile eluted between 0.39% and 0.47% M sodium chloride, and that produced by the other clostridia, between 0.35% and 0.43% M sodium chloride by fast protein liquid chromatography. The latex agglutinating antigen of C difficile was neither cytotoxic nor mouse lethal and was distinct from toxin A and toxin B. In the analysis of faecal specimens from patients with diarrhoea the latex agglutination test correlated better with the presence of C difficile than with toxin B and detected both toxigenic and non-toxigenic strains. The latex agglutination test should only be used in the laboratory as an alternative to culture for C difficile and not as a method for the detection of C difficile toxins.