Real-time quantitative PCR assay for the detection of Helicobacter pylori: no association with sudden infant death syndrome.

Helicobacter pylori infection is known to be one of the most common chronic infectious diseases in humans. Recently, a hypothesis was proposed that H. pylori infection could be a frequent cause for sudden infant death syndrome (SIDS). We have investigated this postulated association by examining formalin-fixed paraffin-embedded gastric tissues of a retrospective cohort of 94 SIDS cases: The presence of H. pylori was inferred from a newly developed real-time quantitative PCR assay with SYBR Green I detection. This assay is based on the amplification of the single-copy H. pylori-specific glmM gene. Accuracy and precision were verified using a plasmid containing a 977-bp fragment of this glmM gene. The assay was very sensitive, and as few as 30 template copies per PCR reaction could be detected even in the presence of excess human DNA. The assay was validated on mucosal biopsy samples of patients with known H. pylori infections. Interfering effects due to SIDS gastric tissue were excluded. Only two (2.1%) of the SIDS samples yielded H. pylori DNA copy numbers and only beyond the lowest standard concentration. These results could be confirmed independently by immunohistochemistry using an H. pylori-specific antibody. Thus, an infection by H. pylori is very rare in cases of SIDS, and thus the postulated association of H. pylori infection and SIDS cannot be confirmed.