Inhibitory effects of various micro-organisms on the growth of Helicobacter pylori

AIMS: To examine the in vitro influence of various bacteria species on Helicobacter pylori (Hp) growth. METHODS AND RESULTS: The effects of 29 micro-organisms on 31 Hp strains were determined using two modified 'cross streak' methods. Staphylococcus epidermidis, Staphylococcus aureus, Pseudomonas aeruginosa, Stenotrophomonas maltophilia, Morganella morganii, Serratia marcescens, Bacteroides fragilis, Fusobacterium nucleatum and Clostridium difficile showed the strongest inhibition. The inhibitory effects varied, depending on the bacteria spp. and Hp strains, and were method dependent. The cagA status of Hp strains did not correlate with the extent of inhibition. CONCLUSIONS: Helicobacter pylori is inhibited by a significant number of commensal bacteria species as well as opportunistic human pathogens. The success and progress of Hp infection may be influenced by the bacterial flora present, while the difficulty in cultivating Hp from the oral mucosa and faeces may be the result of antagonistic bacterial interaction. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provides valuable data on the sensitivity of Hp to a variety of intestinal and oral commensals as well as opportunistic human pathogens. Hp's varying pathogenicity and the specific localization of infection may be the result of these sensitivities. These results can also serve as a basis for further studies to identify the inhibitory substances and make them available for therapeutic use.