Multiple Infection and Microdiversity among Helicobacter pylori Isolates in a Single Host in India

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.

Worldwide Population Structure, Long-Term Demography, and Local Adaptation of Helicobacter pylori

“…However, this empirical observation may be due to an experimental approach that intrinsically limits the detection of multiple infections (Didelot et al 2013) since only a single isolate per patient is generally studied, and more focused approaches have highlighted higher within-host variation (Ghose et al 2005;Patra et al 2012). In addition, MLST studies have detected a small fraction of human hosts from the same population sharing the same bacterial strain (or at least highly related strains with identical sequence type) (Patra et al 2012;Nell et al 2013). At the molecular level, mutation and recombination have been identified as the key forces responsible for population genetic variability (Suerbaum and Josenhans 2007).…”

Genotype Diversity and Quasispecies Development of <i>Helicobacter pylori</i> in a Single Host

“…The genetic variations and conversions may generate additional virulent strains that will colonize an individual host preferentially. Several studies indicated that mixed H. pylori infections may occur in single individuals (7,12,21). In a study by Finger et al in Peru, at least 50z of patients showed infection with 2 H. pylori strains, however 61z of these patients were infected with closely related strains (19).…”

“…Although similarities or differences between H. pylori strains from each patient could be easily predicted by comparing their RAPD patterns, this method does not provide any information about their virulence properties and evolved genetic events. Evolution of H. pylori virulence genes in the human stomach was reported by some studies (1,9,11,12,21,25 …”

Comparative Proteomic Analysis of &lt;i&gt;Helicobacter pylori&lt;/i&gt; Strains Isolated from Chinese Patients

“…Recently, strain variations in H. pylori have been studied at the gene level and compared among different patient groups [3][4][5][6]. In this study, we focused on specific H. pylori proteins derived from patients with gastric cancer and non-gastric cancer.…”

“…Strain diversity among H. pylori isolates has been studied at the gene level, and some reports have shown that H. pylori isolates from different clinical outcomes are genetically diverse with partial virulence factors, which play an important role in pathogenesis [3][4][5][6]. With more complete genomes of H. pylori strains sequenced [7][8][9][10], the information accumulated from genomic studies allows the use of proteomics technologies in studies of these bacteria.…”