From January 2009 to May 2010, 436 faecal samples from patients with diarrhoeal illnessin Southern Ireland were identified as Campylobacter genus-positive by an automated multiplex PCR; however, 204 (46·8%) of these samples were culture-negative for campylobacters. A combination of Campylobacter-specific uniplex PCR and 16S rRNA sequencing confirmed the presence of Campylobacter DNA in 191 (93·6%) of the culture-negative samples. Species-specific PCR identified C. jejuni (50·7%) C. ureolyticus (41%) and C. coli (5·7%) as the most prevalent species while C. fetus, C. upsaliensis, C. hyointestinalis and C. lari accounted for 10% of culture-negative samples; mixed Campylobacter spp. were detected in 11% of samples. We conclude that non-culturable Campylobacter spp. are responsible for a considerable proportion of human enteritis and the true incidence of infection is likely to be significantly underestimated where conventional Campylobacter culture methods are used in isolation.
