Comparisons between degree of histological gastritis and DNA fingerprints, cytotoxicity and adhesivity of Helicobacter pylori from different gastric sites

Abstract

Thirty-six isolates of H. pylori from up to three gastric biopsy sites (antrum, corpus and fundus) from 13 patients in Italy with different degrees of histological gastritis were investigated. All strains were tested for motility, cytotoxicity and degree of adhesion, and were typed by analysis of ribosomal RNA gene patterns (ribopatterns). Seventeen different DNA types (ribotypes) were identified, with each patient possessing H. pylori of one or more unique types. Only two patients had identical H. pylori at three sites. Most patients had H. pylori with different ribotypes or subtypes, but nine strains were not typable. Five patients had the same strain colonizing two of the three sites and atypical strains were mostly from the antrum. A complex pattern of H. pylori colonization in the stomach of some individuals was evident and suggested multiple sources of infection. No consistent associations were detected between degree of gastritis and adherence, cytotoxicity and motility but a 2.56Kb rRNA gene fragment that had a higher frequency in strains associated with severe gastritis than mild gastritis, may provide a useful molecular marker for future pathogenicity studies.

cagA positive and negative Helicobacter pyloristrains are simultaneously present in the stomach of most patients with non-ulcer dyspepsia: relevance to histological damage

“…To avoid the possibility of our results being skewed by differences in culture efficiency of pooled cagA + and cag A− strains, we tested for cag A in several well separated colonies from primary plates per patient. Our results, showing that two thirds of patients harboured both cag A+ and cag A− organisms, are compatible with those obtained by van der Ende et al 16on members of a single family (four of seven members harboured cag A+ and cag A− colonies), and are supported by an earlier study on genomic variety of H pylori strains isolated from different gastric sites of the same patients, a study that showed that 85% of 13 Italian patients were colonised by strains with different ribotypes 18. The latter study, however, also suggests that cag A+ and cag A− organisms from the same patient may be different strains 18.…”

“…However, seropositivity for VacA and CagA does not determine the composition of the bacterial population in the stomach, and the characteristics of a single clone cannot be extrapolated to all the helicobacters colonising the same organ. As there is evidence that bacterial phenotypic variety and genomic macro- or micro-diversity can exist within the stomach of a single patient,11 18 23 it was important to determine whether strains with different expression of cag A could colonise the same patients at the same time. A number of investigators have tackled this problem, but we believe that the frequency of mixed cultures that they observed was probably underestimated,9 15-18 partly because, in some cases, pooled colonies had been stored at − 70°C before the tests were carried out.…”

“…Mixed infections by phenotypically or genotypically different strains are not rare. For instance, cytotoxic and non-cytotoxic H pylori strains were found at the same time in the same biopsy samples of about one third of the patients examined,11 and strains with the same ribotype were found in different gastric areas (antrum, corpus, and fundus) of single patients in only two of the 13 infected individuals examined 18. Cytotoxigenicity and the possession of the cag A gene are important characteristics which could enable these bacteria to preferentially colonise certain areas of the stomach where they may enjoy a selective benefit.…”

Absence of translationally selected synonymous codon usage bias in Helicobacter pylori

“…Multiple infections by different strains of Hel. pylori (Beji et al, 1989 ;Owen et al, 1993 ;Fujimoto et al, 1994 ;Akopyants et al, 1995 ;Taylor et al, 1995 ;, as well as localized mixed occurrences (Kitamoto et al, 1998 ;J. C. Atherton, unpublished) have been reported, but there is no evidence that these strains compete via exponential growth.…”

Population genetic analysis of Helicobacter pylori by multilocus enzyme electrophoresis: extensive allelic diversity and recombinational population structure

“…Data obtained by biotyping (28), plasmid profiling (42,55), restriction fragment length polymorphism analysis of genomic DNA (1,26,30,42,43,47,49,58) and specific loci (2,11,13,14,18,20,22,48,59), and repetitive extragenic palindromic PCR (REP-PCR) (23) have shown that there are substantial levels of variation among natural isolates of this pathogen. However, several important questions remain unanswered about the diversity observed among H. pylori isolates.…”