High Prevalence of Campylobacter ureolyticus in Stool Specimens of Children with Diarrhea in Japan.

Campylobacter ureolyticus has been considered as a potentially pathogenic bacterium. In this study, a total of 586 stool samples were collected from 0-12-year-old children with diarrhea between November 2013 and April 2015 and examined with microbiological tests in the hospital for the diagnosis of common enteric pathogens including C. jejuni and C. coli. Then in our laboratory, these samples were analyzed by 16S rRNA sequence-based Campylobacter genus-specific PCR (C16S PCR); 283 (48.3%) samples showed positive results with this PCR assay. Furthermore, C. ureolyticus was screened in these 283 samples by PCR assay, which can detect this species specifically. Surprisingly, C. ureolyticus was detected in 147 of the 283 C16S PCR-positive diarrheal stool samples (51.9%), which is much higher than the prevalence of C. jejuni and C. coli (15.5%), and 96 samples out of 147 were negative for any of the other enteric pathogens tested in the hospital; namely, C. ureolyticus was detected as a single pathogen in 96 samples. This finding suggests that C. ureolyticus may be a pathogen associated with diarrhea in children in Japan. To the best of our knowledge, this is the first report in which C. ureolyticus was detected among Japanese children with diarrhea.