Cytotoxic and cytotonic factors produced by Campylobacter jejuni, Campylobacter coli, and Campylobacter laridis.

Complete toxigenicity studies were performed on 341 strains of Campylobacter spp., including 23 nonhuman isolates. Toxin profiles based on both cytotonic and cytotoxic factors were determined after analyzing responses in Vero, HeLa, CHO and Y-1 cells. Suckling mouse assays were consistently negative for all culture filtrates tested. Toxin-producing strains were frequently encountered among both the human and nonhuman strains of Campylobacter jejuni, C. coli, and C. laridis investigated. Strains isolated from outbreaks demonstrated parallels in serotype, biotype, and toxigenicity profile, although no clear association could be demonstrated. Biphasic culture conditions conducive to the production of both toxic factors were delineated for the propagation of test Campylobacter strains. Cytotonic effects of Campylobacter culture filtrates were determined in Vero and CHO cells, and cyclic AMP accumulation in cells exposed to these culture filtrates was compared with that in cells exposed to reference toxigenic strains of Vibrio cholerae and Escherichia coli. Partial neutralization of C. jejuni enterotoxin was demonstrated by using antitoxins to cholera toxin and E. coli heat-labile enterotoxin. No neutralization of C. jejuni cytotoxin could be achieved by using antitoxins to either Clostridium difficile cytotoxin or E. coli Verotoxin (0157:H7).