Original Articles
Copyright ©The Author(s) 2001. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Apr 15, 2001; 7(2): 254-258
Published online Apr 15, 2001. doi: 10.3748/wjg.v7.i2.254
Virulence and potential pathogenicity of coccoid Helicobacter pylori induced by antibiotics
Fei-Fei She, Dong-Hui Su, Jian-Yin Lin, Lin-Ying Zhou
Fei-Fei She, Dong-Hui Su, Department of Microbiology, Fujian Medical University, Fuzhou 350004, Fujian Province, China
Jian-Yin Lin, Department of Molecular Medicine, Fujian Medical University, Fuzhou 350004, Fujian Province, China
Lin-Ying Zhou, Laboratory of Electron Microscope, Fujian Medical University, Fuzhou 350004, Fujian Province, China
Fei-Fei She, graduated from Fujian Medical University as a postgraduate in 1991, now associate professor of microbiology and immunology, specialized in molecular biology of pathogen, having 15 papers published.
Author contributions: All authors contributed equally to the work.
Supported by the Natural Science Foundation of Fujian Province, China, No. 95A003
Correspondence to: Fei-Fei She, Department of Microbiology, Fujian Medical University, Fuzhou 350004, Fujian Province, China
Telephone: +86-591-3569309
Received: November 15, 2000
Revised: February 22, 2000
Accepted: December 30, 2000
Published online: April 15, 2001
Abstract

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 alldecreased. 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 Mr 125000 weakened, while the band Mr 110000 and Mr 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 Mr 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.

Keywords: Helicobacter pylori/drug; Helicobacter pylori/pathogenicity; antibiotics/pharmacology; polymerase chain reaction