Co-colonization of non-Helicobacter Bacteria and Helicobacter pylori in Patients with Gastritis

Understanding the bacterial community composition of gastric microbes and the relationship between its differences in the development and progression of gastritis can be of great help in the perception of the mechanism of this disease and designing preventive treatment pathways for its progression. We aimed to investigate the simultaneous colonization of bacterial agents in patients with chronic gastritis.

The study was performed on 168 gastric biopsy specimens of patients with gastric complaints who were referred to the endoscopic ward of Firoozgar hospital in Tehran. Biopsy specimens in the pathology department were examined histologically by the hematoxylin-eosin staining method and in the specific culture medium of Helicobacter under microaerophilic growth conditions and in general culture medium under aerobic conditions for the presence of Helicobacter and other bacteria. Identification of Helicobacter pylori (H. pylori) isolates was performed by analyzing colony morphology, gram staining, positive reactions of oxidase and catalase, rapid urease test, and polymerase chain reaction (PCR). Other bacteria were identified by biochemical and phenotypical analysis.

In our study, the recovery rate of H. pylori infection was 27.4 %. The mean age of patients in the two groups with and without H. pylori infection was almost the same. 87.5% of all patients had chronic gastritis, which showed significant associations with H. pylori infection (p-value: 0.00). We identified 140 bacterial colonies that belonged to 12 genera and 3 phyla. At the genus level, Streptococcus and Staphylococcus were predominant followed by Micrococcus, Escherichia coli, Bacillus, Enterococcus, Klebsiella, Pseudomonas, Enterobacter, Citrobacter, and Providencia. The predominant phyla were Proteobacteria and Firmicutes while Actinobacteria was less frequent. Co-infection of H. pylori with other isolated bacteria, especially Streptococcus and Staphylococcus was observed.

The presence of different bacterial genera in the gastric tissue of patients with gastritis in the absence of H. pylori suggests their possible role in the occurrence or progression of this disease. Additional studies to determine the association of the persistence of these bacteria with the use of drugs that modulate gastric acidity and pathological changes can be useful in the prevention and treatment of gastritis.