Urease Activity and Urea Gene Sequencing of Coccoid Forms of H. pylori Induced by Different Factors |
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Authors: | Fusun Can Ceren Karahan Istar Dolapci Muge Demirbilek Alper Tekeli Hande Arslan |
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Institution: | (1) Department of Microbiology and Clinical Microbiology, Baskent University School of Medicine, Ankara, Turkey;(2) Department of Microbiology and Clinical Microbiology, Ankara University School of Medicine, Ankara, Turkey;(3) Baskent Universitesi Tip Fakultesi Baglica Kampusu, Eskisehir yolu 20.Km, Etimesgut, Ankara, Turkey |
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Abstract: | Helicobacter pylori exists in two morphologic forms: spiral shaped and coccoid. The nonculturable coccoid forms were believed to be the morphologic
manifestations of cell death for a long time. However, recent studies indicate the viability of such forms. This form of H. pylori is now suspected to play a role in the transmission of the bacteria and is partly responsible for relapse of infection after
antimicrobial treatment. Urease activity of H. pylori is an important maintenance factor. Determination of urease activity and possible mutations in the DNA sequences of coccoid
bacteria will hence contribute to the understanding of pathogenesis of infections, which these forms might be responsible
for. In this study, our aim was to analyze the urease activity and investigate the urease gene sequences of coccoid H. pylori forms induced by different factors with respect to the spiral form. For this purpose, the urease activities of H. pylori NCTC 11637 standard strain and two clinical isolates were examined before and after transformation of the cells to coccoid
forms by different methods such as exposure to amoxicillin, aerobiosis, cold starvation, and aging. The effects of these conditions
on the urease gene were examined by the amplification of 411-bp ureA gene and 115-bp ureB gene regions by PCR technique and sequencing of the ureA gene. The urease activities of coccoid cells were found to be lower than those of the spiral form. ureA and ureB gene regions were amplified in all coccoid cells by PCR. Inducing the change to coccoid form by different methods was found
to have no effect on the nucleotide sequence of the ureA gene. These results show that the urease gene region of coccoid H. pylori is highly protected under various mild environmental conditions. |
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