Virulence and potential pathogenicity of coccoid Helicobacter pylori induced by antibiotics

AIM: To explore the virulence and the potential pathogenicity of coccoid Helicobacter pylori (H. pylori) transformed from spiral form by exposure to antibiotic. METHODS: Three strains of H. pylori, isolated from gastric biopsy specimens of confirmed peptic ulcer, were converted from spiral into coccoid from by exposure to metronidazole. Both spiral and coccoid form of H. pylori were tested for the urease activity, the adherence to Hep-2 cells and the vacuolating cytotoxicity to Hela cells, and the differences of the protein were analysed by SDS-PAGE and Western blot. The mutation of the genes including ureA, ureB,hpaA, vacA and cagA, related with virulence, was detected by means of PCR and PCR-SSCP. RESULTS: In the coccoid H. pylori,the urease activity, the adherence to Hep-2 cells and the vacuolating cytotoxicity to Hela cells all decreased. In strain F44, the rate and index of adherence reduced from 70.0% +/- 5.3% to 33% +/- 5.1% and from 2.6 +/- 0.4 to 0.96 +/- 0.3 (P 【 0.01), respectively. The invasion of coccoid H. pylori into Hep-2 cell could be seen under electronmicroscope. SDS-PAGE showed that the content of the protein with the molecular weight over Mr 74000 decreased, and the hybriditional signal in band M(r) 125000 weakened, while the band M(r)110000 and M(r)63000 strengthened in coccoid H.pylori as shown in Western blot. The results of PCR were all positive, and PCR-SSCP indicated that there may exist the point mutation in gene hpaA or vacA. CONCLUSION: The virulence and the proteins with molecular weight over M(r)74000 in coccoid H.pylori decrease, but no deletion exists in amplification fragments from ureA, ureB, hpaA, vacA and cagA genes, suggesting that coccoid H.pylori may have potential pathogenicity.

Association of CagA and VacA presence with ulcer and non-ulcer dyspepsia in a Turkish population

AIM:The mostly known genotypic virulence features,of H.pylori are cytotoxin associated gene A (cagA) and Vacuolating cytotoxin gene A (VacA).We investigated the association of these major virulence factors with ulcer and non-ulcer dyspepsia in our region. METHODS:One hundred and forty two dyspeptic patients were studied (average age 44.8±15.9 years,range 15-87 years,64 males and 78 females).Antral and corpus biopsies were taken for detecting and genotyping of H.pylori.107 patients who were H.pylori positive by histological assessment were divided into three groups according to endoscopic findings:Duodenal ulcer (DU),gastric ulcer (GU) and non-ulcer dyspepsia (NUD).The polymerase chain reaction (PCR) was used to detect CagA and VacA genes of H.pylori using specific primers. RESULTS:H.pyloriwas isolated from 75.4% (107/142) of the patients.Of the 107 patients,66 (61.7%) were cagA- positive and 82 (76.6%) were VacA-positive.CagA gene was positively associated with DU and GU (P<0.01,P<0.02), but not with NUD (P>0.05).Although VacA positivity in ulcer patients was higher than that in NUD group,the difference was not statistically significant (P>0.05). CONCLUSION:There is a significantly positive association between CagA genes and DU and GU.The presence of VacA is not a predictive marker for DU,GU,and NUD in our patients.

Comparison of three PCR methods for detection of Helicobacter pylori DNA and detection of cagA gene in gastric biopsy specimens

AIM:To comparatively evaluate PCR and other diagnostic methods (the rapid urease test and/or culture) in order to determine which of the three PCR methods (ureA,glmM and 26-kDa,SSA gene) was most appropriate in the diagnosis of Helicobacterpylori(Hpylori) infection and also to evaluate the detection of a putative virulence marker of H pylori,the cage,gene,by PCR in biopsy specimens. METHODS:One hundred and eighty-nine biopsy specimens were collected from 63 patients (three biopsies each) undergoing upper gastroduodenal endoscopy for various dyspeptic symptoms.The PCR methods used to detect H pylori DNA directly from biopsies were the glmM,26-kDa, ureA and then cagA was used to compare the culture technique and CLO for urease with the culture technique being used as the gold standard. RESULTS:Thirty-five percent of the biopsies were positive for H pylori DNA using the 3 PCR methods,while 68% of these were positive for the cagA gene.Twenty-four percent of the biopsies were negative for H pylori DNA in all PCR methods screened.The remaining 41% were either positive for ureA gene only,glmM only,26-kDa only,or ureA+glmM, ureA+26-kDa,glmM+26-kDa.Out of the 35% positive biopsies,41% and 82% were positive by culture and CLO respectively,while all negative biopsies were also negative by culture and cagA.Cag A+ infection was also predominantly found in H pylori DNA of the biopsies irrespective of the clinical diagnosis. CONCLUSION:This method is useful for correctly identifying infections caused by H pylori and can be easily applied in our laboratory for diagnostic purposes.

Helicobacter pylori antigen and its IgG, IgA -type specific immunocomplexes in sera from patients with Helicobacter pylori infection

OBJECTIVE: To explore the characteristics of Helicobacter pylori (H. pylori) antigen in serum and to evaluate its clinical diagnostic value. METHODS: Enzyme-linked immunosorbant assay (ELISA) was developed to detect the soluble H. pylori antigen (S-Hp) and circulatory specific H. pylori antigen immunocomplexes (Hp-IC) in serum. RESULTS: The positive rate of S-Hp was 90.91% from 66 patients with H. pylori infection, which was much greater than 0% found in 28 controls (P