Molecular typing ofHelicobacter pyloriisolates from asymptomatic, ulcer and gastritis patients by urease gene polymorphism

Abstract

SUMMARYThe gastric-adapted bacterium Helicobacter pylori plays an important role in gastritis and ulcer disease, but no phenotypic typing scheme presently exists for this organism. With a view to the development of genotypic typing, we have compared isolates of H. pytori from gastritis or ulcer patients with those from subjects exhibiting no disease. Variation was analysed at the urease genes, ureA and ureCD, by employing PCR-generated probes in genomic Southern blot hybridizations. Whilst ureA restriction fragments provided a fourfold subgrouping of strains, ureCD fragments were considerably more discriminatory. Twenty-four combined ureACD profiles were generated with Hind III, subdividing the 64 strains into 11 types and 13 single profiles. The most prevalent profile (UI) was found in 33 % of strains, almost all from gastritis or ulcer patients. On the other hand strains isolated from asymptomatic individuals had the most diverse ureACD profiles. A key finding from this set of isolates was that strains of H. pylori associated with general gastroduodenal disease were genetically more homogeneous than strains carried by people without disease symptoms. INTRODUCTIONThe Gram-negative bacterium Helicobacter pylori was first isolated in 1982 by Warren and Marshall [1]. Endoscopic and seroprevalence analyses indicate that this organism has a worldwide distribution, and is frequently isolated from asymptomatic persons [2]. By the age of 60 years, 40-60% of adult humans in developed countries show evidence of H. pylori infection without necessarily showing signs of disease [3]. The presence of the bacterium has however been causally associated with type B gastritis and is a contributing factor in peptic

Allelic variation in theHelicobacter pyloriflagellin genesflaA andflaB: its consequences for strain typing schemes and population structure

“…Numerous studies have noted the extensive genetic diversity of this organism, with the identification of indistinguishable strains in different hosts being generally uncommon. This diversity is observable by many different methods: pulsed field gel electrophoretic (PFGE) separation of large genomic DNA fragments [5], PCR amplification of random chromosomal DNA sequences (RAPD-PCR) [6], PCR amplification of specific genes such as urease or flagellin [7,8].…”

Genetic Variability Determinants ofHelicobacter pylori:Influence of Clinical Background and Geographic Origin of Isolates

“…Considering that only 10%-20% of people infected with H. pylori develop overt disease, reliable identification of strains would indeed be very beneficial [31]. Earlier reports that used a wide array of techniques have characterized H. pylori as a highly variable species that appears to consist of innumerable individual strains, each with their own distinctive genotype [7,9,10,15,32,33]. Among the explanations suggested to account for this striking variability are single point mutations, either silent or those that result in an amino-acid substitution, and recombination events that involve horizontal gene transfer, which could occur as a result of transformation, conjugation, or transduction [7,11,14].…”

Genetic diversity of canine gastric helicobacters, Helicobacter bizzozeronii and H. salomonis studied by pulsed-field gel electrophoresis

“…Similar sizes were estimated from NotI and SpeI digests. Fragments from NotI digests were fewer (2-4) than fiom SpeI digests (14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25).…”

“…The genome of H. pylori has been characterised and the whole genome sequence analysis has been published recently [ 81. The intra-species genetic diversity has been studied also by various genetic methods such as macrorestriction analysis of the whole genome by pulsedfield gel electrophoresis (PFGE) [9, 101, by multi-locus enzyme electrophoresis (MLEE) [ 1 11, ribotyping [ 121, randomly amplified polymorphic DNA [ 131 and polymorphism of urease [ 14,151 and vacA [ 161 genes. All these methods have revealed significant genetic diversity, probably a necessary characteristic for a pathogen adapted to one mammal species, man.…”