Long-term colonization with single and multiple strains of Helicobacter pylori assessed by DNA fingerprinting

Abstract

The gastric pathogen Helicobacter pylori establishes long-term chronic infections that can lead to gastritis, peptic ulcers, and cancer. The species is so diverse that distinctly different strains are generally recovered from each patient. To better understand the dynamics of long-term carriage, we characterized H. pylori isolates from initial and follow-up biopsy specimens from a patient population at high risk of H. pylori infection and gastric cancer. Eighty-five isolates were obtained from 23 patients and were analyzed by genomic restriction enzyme analysis, arbitrarily primed PCR fingerprinting, (random amplified polymorphic DNA analysis), and/or restriction of specific PCR-amplified genes (restriction fragment length polymorphism analysis). A single strain was found in sequential biopsy specimens from 12 of 15 patients (80%) receiving sucralfate. In the remaining three patients treated with sucralfate, two strains were identified in two patients and three strains were identified in the third patient. In contrast, a single strain was found in sequential biopsy specimens from only three of eight patients (37%) receiving bismuth, metronidazole, and nitrofurantoin. Two strains were identified in five other patients receiving bismuth-antibiotic (63%). Immunoglobulin G antibodies to H. pylori were present in the sera of all patients. Thus, H. pylori colonization can persist for long periods (up to at least 4 years), despite high titers of immunoglobulin G antibodies in serum. Resistance to metronidazole was noted in some strains before and/or after treatment, but all strains remained susceptible to amoxicillin, tetracycline, and nitrofurantoin. We conclude that H. pylori genotypes, as measured by several sensitive DNA fingerprinting methods, can remain stable for years in vivo, despite the acquisition or loss of drug resistance, circulating antibody, or exposure to antibiotics or sucralfate.

The Prevalence of Mixed Helicobacter pylori Infections in Symptomatic and Asymptomatic Subjects in Dhaka, Bangladesh

“…We found high mixed infection rate in our study population. We speculate that mixed infection was generated by frequent recombination; this is supported by the observation that patients can be simultaneously colonized with strains that differ in their randomly amplified polymorphic DNA pattern [30,31]. Even if most individuals were infected with H. pylori early in childhood and harbored their individual strain thereafter, occasional mixed colonization and transformation would lead to extensive genetic rearrangements through time.…”

Dynamics of the Cag-type IV secretion system ofHelicobacter pylorias studied by bacterial co-infections

“…After having injected CagA into a defined host cell, this cell should be protected against injection of CagA by the same or another individual bacterium of the same strain. However, the human stomach can also be exposed to multiple infections with different H. pylori strains at the same time (Taylor et al, 1995), or to different other bacterial species, as shown by microbiome studies (Bik et al, 2006;Maldonado-Contreras et al, 2011). A recent study in The Gambia reported about a high prevalence of H. pylori in dyspeptic patients with many isolates belong-ing to the putatively more virulent cagA + , vacAs1 and vacAm1 genotypes.…”

Co‐Existing Gastric Cancer and Duodenal Ulcer Disease: Role of Helicobactor pylori Infection

“…One possibility is that mixed infection occurs with both duodenal ulcer and gastric cancer strains. Mixed infection with several strains has certainly been demonstrated and if disease-specific strains occur and circulate with different frequencies in different populations, Korea with its high frequency of both diseases would be one site where coinfection with strains with a propensity to lead to each of the diseases would not be unlikely [32][33][34][35]. Recent studies comparing cagA gene in H. pylori strains from Korea and the United States found that the pattern of the strains from Korea was different from that in the U.S. suggesting that the predominant circulating strain may vary markedly between geographic regions [36].…”