L-forms of H. pylori

Determination of the prevalence of Helicobacter heilmannii-like organisms type 2 (HHLO-2) infection in humans and dogs using non-invasive genus/species-specific PCR in Korea

Helicobacter spp. may have multiple routes of transmission. It is unclear, however, whether the agent is zoonotic and therefore transmitted from an animal reservoir, including dogs. The aim of this population-based study was to assess the relationship between pet ownership or frequent exposure to dogs and Helicobacter spp. infection, especially focusing on HHLO-2 (Helicobacter heilmannii-like organisms type 2) in saliva and feces samples in Korea, using non-invasive genus/species-specific PCR. One hundred twenty-four eligible human subjects and 39 dogs participated in this study. Relativity of contact with dogs and Helicobacter spp. infection diagnosed by genus-specific PCR showed a statistically significant result (P<0.01), but in the relativity analyses between contact with dogs and H. pylori, H. felis and H. bizzozeronii infections diagnosed using species-specific PCR, only Helicobacter felis showed a statistically significant result. Although H. pylori infection showed a statistically significant relativity, no statistically significant association was found between veterinarian subjects and Helicobacter. spp., H. felis and H. bizzozeronii infections. On performing risk factor analyses of HHLO-2 infection by transmission, using matching species, between HHLO-2-positive dog owners and HHLO-2-positive dogs, Helicobacter felis infection showed an extremely significant relativity (P<0.0001), and Helicobacter bizzozeronii may also be a possible significant risk factor (P<0.01). These results suggest that HHLO-2 infection might be a zoonotic infection, because continuous contact with dogs was proved to be correlated with human H. felis and H. bizzozeronii infections in this study.

Survival advantage in hosts with H. pylori infection

AIM: To study the in vitro killing effects of cecropin-like antibacterial peptide from H. pylori Hp (2-20) on the gastrointestinal bacterial pathogens and to explore the survival advantage to the host of infection with H. pylori.

METHODS: The inhibition zone assay was used to determine anti-bacterial activity and lethal concentrations of H. pylori antibacterial peptide Hp (2-20) on the gastrointestinal bacterial pathogens. The rate of killing of E.coli K₁₂D₃₁ (standard strain) by Hp (2-20) was estimated by counting viable bacteria based on counting of colonies grown in Luria-Bertani plate. The cytotoxicity of the Hp (2-20) peptides on human gastric epithelial cell line was measured by trypan blue exclusion test.

RESULTS: In vitro studies, the Hp (2-20) destroyed the gastrointestinal bacterial pathogens such as Shigella flexneri, Salmonella typhi, Salmonella paratyphi and enteropathogenic E.coli. The lethal concentrations (LC) were 65-197 mmoL/L. The viable bacterial count dropped to zero after 12 min incubation with Hp (2-20) concentration closed to the LC value. The Hp (2-20) was inactive against the strains of Yersinia enterocolitica and Staphylococcus aureus and had much higher LC (over 1014mmol/L). The killing effects of Cecropin B were more pronounced than Helicobacter peptide Hp (2-20). The synthetic peptideHp(2-20) showed no lytic or toxic activity against the human gastric epithelial cell line GES-1.

CONCLUSION: The cecropin-like antibacterial peptide from H. pylori Hp (2-20) is active against faster-growing gastrointestinal bacterial pathogens. There is no effect on the human gastric epithelial cells. H. pylori may actually have beneficial effects on infected carriers who are heavily exposed to other gastrointestinal pathogens.