Campylobacter jejuni infection within a laboratory animal production unit

A conventional laboratory animal production unit in which rats, mice, guineapigs and rabbits were bred in one building and cats maintained in a separate, but adjacent area was examined for the presence of intestinal thermophilic Campylobacter spp. Campylobacter jejuni was recovered from 18.84% of 552 animals. The infection rate was highest amongst the cats (51.7%), with rats being the second most commonly infected (23.2%), whereas only 7.7% of guineapigs and a single rabbit (1%) were positive. Campylobacter-like organisms were cultured from 10% of the mice, but these bacteria failed to grow on subsequent subculturing. By using bacterial restriction endonuclease DNA analysis (BRENDA), a single type of C. jejuni was identified from all isolates recovered from the rats, guineapigs and a rabbit, suggesting a common source of infection. In contrast, there were 5 different BRENDA patterns derived from cat isolates. No isolates of C. jejuni were obtained from humans working within the unit or from animal bedding or the immediate environment, although it was suggested that the organism may have entered and spread within the unit from sawdust.