Multiple infection and microdiversity among Helicobacter pylori isolates in a single host in India

PLoS One. 2012;7(8):e43370. doi: 10.1371/journal.pone.0043370. Epub 2012 Aug 27.

Abstract

Helicobacter pylori is one of the most diverse bacterial species that chronically infects more than 70% of Indian population. Interestingly, data showing microdiversity of the H. pylori strains within a particular gastric niche remained scarce. To understand the extent of genetic diversity among H. pylori strains within a given host, 30 patients with gastro-duodenal problems were subjected to endoscopy and from each patient 10 single colonies were isolated. Characterization of each of these 10 single colonies by DNA fingerprinting as well as genotyping of several important genetic markers viz. cagA, vacA, iceA, vapD, cag PAI empty site, IS605, RFLP and two other genetic segments within cag PAI revealed that all of the 30 patients were infected with more than one strain and sometimes strains with 5 to 6 types of genetic variants. Analyses of certain genetic loci showed the microdiversity among the colonies from single patient, which may be due to the recombination events during long-term carriage of the pathogen. These results suggest that most of the patients have acquired H. pylori due to repeated exposure to this pathogen with different genetic make-up, which may increase the possibility of super infections. Genetic exchanges between these unrelated H. pylori strains may support certain H. pylori variant to grow better in a given host than the parental strain and thereby increasing the possibility for the severity of the infection.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antigens, Bacterial
  • Biodiversity
  • DNA Primers / genetics
  • Duodenum / microbiology
  • Endoscopy / methods
  • Genetic Markers
  • Genetic Variation
  • Genotype
  • Helicobacter Infections / epidemiology*
  • Helicobacter Infections / microbiology*
  • Helicobacter pylori / metabolism*
  • Humans
  • Polymerase Chain Reaction / methods
  • Polymorphism, Genetic
  • Recombination, Genetic
  • Sequence Analysis, DNA
  • Stomach / microbiology
  • Virulence

Substances

  • Antigens, Bacterial
  • DNA Primers
  • Genetic Markers

Grants and funding

The work was supported in part by the Indian Council of Medical Research and Department of Biotechnology, India (Sanction No. BT/PR10407/BRB/10/604/2008). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.