Objective: Heterogeneity among Helicobacter pylori (H. pylori) strains in the expression of CagA and outer membrane proteins (OMPs) is an important factor influencing clinical outcomes. We investigated the expression of H. pylori cagA, omp6 (hopA), omp13 (oipA), omp18, and omp20 (alpA) genes and their associations with clinicopathological findings.

Materials and Methods: Endoscopic biopsies from the gastric antrum and corpus of 120 patients were initially examined using a rapid urease test (RUT), histopathology, and culture. Biopsy specimens from 101 patients were analyzed for H. pylori cagA, omp6, omp13, omp18, omp20, 16S rRNA, and ureA gene expression by Real-Time Reverse Transcription-Polymerase Chain Reaction (RT-PCR). Total RNA was extracted from antral and corpus biopsies and cDNA was synthesized.

Results: Forty-eight patients were positive for H. pylori infection based on both RUT and histopathology or culture positivity. H. pylori was detected in 77 of 101 (76.2%) patients by RT-PCR. Of the 48 patients with H. pylori infection, 45 (93.7%) were RT-PCR positive. The gene expression frequencies of cagA, omp6, omp13, omp18, and omp20 in the antrum and corpus of 45 patients were 30 (66.7%), 35 (77.8%), 37 (82.2%), 45 (100.0%), and 37 (82.2%), respectively. No significant association was found between gene expression frequency and endoscopic findings. However, the expression level of the omp13 gene was significantly lower in patients with gastric ulcers than in patients with non-erosive gastritis. There was no association between gene expression frequency or level and histopathological parameters. The expression levels of the omp6 and omp13 genes were significantly higher in the corpus than in the antrum.

Conclusions: Neither cagA nor OMPs gene expression had a statistically significant impact on patient’s clinical outcomes in our hospital. The omp6 and omp13 genes may play an important role in the pathogenesis of H. pylori infection.