Numerous studies have shown significant variability of the gastric microbial communities with respect to H. pylori status. One such study was carried out by Osaki et al., who examined the gastric microbiota of H. pylori-positive and H. pylori-negative Mongolian gerbils. The study showed a larger number of Bifid bacterium spp. in H. pylori-positive gerbils, compared to the H. pylori-negative, while Eubacteriacylindroids and Prevotella spp. were only found in the H. pylori-negative group(Guinane, C. M., & Cotter, P. D. 2013) (Camargo, M. C., et al 2019).
Several mouse model studies have also shown clear differences in the composition of the gastric microbiota with respect to H. pylori status. Infection by H. pylori of pathogen-free female BALB/c mice has been shown to reduce the Lactobacillus spp. in the gastric micro flora. In transgenic, insulin-gastrin (INS-GAS) mice, the H. pylori-infected male mice show a significantly different phyla compared to the non-infected control group, with an increase in Firmicutes and a decrease in Bacteroidetes. Findings in H. pylori-colonized C57BL/6 N female mice included reductions in Firmicutes (class Bacilli), Bacteroidetes, and Proteobacteriaand an increase of Firmicutes (class Clostridia), Proteobacteria (genus Helicobacter), and Verrucomicrobia. However, other published data on the murine gastric microbiota suggest that neither acute nor chronic H. pylori infection substantially modifies the gastric microbial ecosystem.
A few studies have also examined H. pylori-related microbial differences in humans. One study found relative abundances of Proteobacteria, Spirochetes, and Acidobacteria in H. pylori-positive patients, compared to the control H. pylori-negative group. Another study demonstrated that patient’s positive for H. pyloriculture showed significantly increased colonization of Proteobacteria and a decrease in Actinobacteria (Hold, G. L., & Hansen, R. 2019).