Molecular identification of Helicobacter DNA present in human colorectal adenocarcinomas by 16S rDNA PCR amplification and pyrosequencing analysis

Abstract

Seroepidemiological studies have indicated thatHelicobacter pyloriinfection might be a possible risk factor for colorectal adenocarcinoma (CRC) development. However, limited information is available as to whether or notHelicobacterspecies are present in CRC tissues. In this study the presence ofHelicobacterDNA in 77 CRC biopsies was investigated by means of aHelicobacterspecies-specific 16S rDNA PCR assay and real-time DNA pyrosequencing of the 16S rDNA variable V3 region. Pyrosequencing revealed the presence ofHelicobacterDNA sequences in 21 of 77 biopsy specimens (27 %). 16S rDNA sequences corresponding toH. pylori26695 andH. pyloriJ99 were most commonly found. Intriguingly, one sequence belonged toHelicobacter mustelae, previously identified in ferrets. No significant correlations were found in the prevalence ofHelicobacterDNA between colon and rectum tumour biopsies (P= 0.815), nor between Dukes’ classes A/B and C/D (P= 0.262). 16S rDNA PCR amplification combined with pyrosequencing analysis of 16S rDNA variable V3 regions provides a powerful molecular tool to identifyHelicobacterspecies in human biopsy specimens.