Assessment of the survival rate of non-cultivable forms of Helicobacter pylori in water samples

H. Pylori is an important cause of human peptic ulcers and stomach cancers. Once the bacterium is placed in the water, it changes into a viable, but non-cultivable coccoid form, which is considered as an important factor to spread out the infection. The aim of this study was to evaluate the survival rate of coccoid forms of H. pylori in water samples, using PCR and culture methods. This experimental study was performed on 10 strains of H. pylori isolated from clinical specimens. Isolates were added to water at the temperatures of 4°C, 22°C, and 37°C and incubated at intervals of 1 and 2 months. Each time, the samples were cultured on Brucella blood Agar medium. Following DNA extraction, the presence of glmM gene was confirmed using PCR method. Furthermore, the sensitivity and specificity of PCR method were evaluated. While
culturing in first month at 4°C showed no H. pylori coccoid growth on medium, some positive results (growth rate of 10% and 20%, respectively) were detected at 22°C and 37°C during the same month. No positive result was obtained during the second month. Performing PCR, with more sensitivity as compared to culturing method, identified H. pylori coccoid growth of 10%, 30%, and 40%, for the first month, and 0%, 20%, and 30% for the second month at 4°C, 22°C, and 37°C, respectively. The results of this study showed that the non-cultivable cocoid forms of H. pylori in water can be detected by non-culturing methods such as PCR which is sensitive, specific, and accurate.