Pathogenicity of Campylobacter jejuni isolates from animals and humans.

Fourteen isolates of Campylobacter jejuni of different serotypes and one Campylobacter coli isolate, from various human and animal sources, were tested for potential pathogenic mechanisms. Enterotoxin production was not detected in the infant mouse test or by calf and piglet ligated intestinal loop studies. Isolates were not invasive by the Sereny test. All isolates associated with and penetrated HeLa cells, although both actions occurred generally in a minor way under the conditions of our study. The C. coli isolate showed extensive HeLa cell association, but three other C. coli isolated tested did not. None of the 15 isolates produced diarrhea or death in 3-day-old chickens inoculated orally and observed for 3 days, nor did they consistently produce diarrhea and death in 9- to 10-day-old infant mice over a 3-day period after oral inoculation. Diarrheal disease and mortality were not observed when 3-day-old gnotobiotic chickens were infected with one of five isolates and observed over a 2-week period.