Increased rate of Helicobacter pylori infection detected by PCR in biopsies with chronic gastritis

Histology is considered a sensitive method for detection of Helicobacter pylori, in gastric biopsies. We investigated the diagnostic potential of qualitative nested (nPCR) and quantitative PCR (qPCR) for detection of H. pylori using different primers on 126 archived gastric biopsies with inflammation and correlated the inflammatory changes with the presence and density of bacteria. H. pylori was detected in 42.8% biopsies by histology and PCR, an additional 15 samples were positive exclusively by PCR: nPCR was positive in all histologically positive samples, but qPCR failed to detect H. pylori in 10 biopsies. The inflammatory score was significantly higher in biopsies positive for H. pylori only by PCR showed a significant higher inflammatory score compared with negative biopsies (mean of neutrophils score, 1.60 vs. 0.90, P < 0.01; mean of mononuclear cells score, 2.27 vs. 1.67, P < 0.01), whereas the inflammatory score was similar compared with biopsies positive for H. pylori by histology (mean of neutrophils score, 1.60 vs. 1.56, not significant; mean of mononuclear cells score, 2.27 vs. 2.20, not significant). A weak correlation between inflammatory score and the density of H. pylori detected by histology was observed. The mean values of H. pylori DNA were significantly higher in histologic-positive than in histologic negative biopsies. We have shown that PCR can detect H. pylori in about 20% of histologic-negative gastric biopsies, indicating the clinical relevance of H. pylori detection by PCR in biopsies with characteristic inflammatory changes.