Chi-Tan Hu a, b, Pei-Yu Chiou c, Chao-Chuan Wu d, Yi-Hsiung Tseng e, Yao-Jen Chang d, Nien-Tsung Lin f
aDepartment of Gastroenterology, Buddhist Tzu Chi General Hospital, Hualien, Taiwan
bDepartment of Internal Medicine, Tzu Chi University, Hualien, Taiwan
cInstitute of Medical Sciences, Tzu Chi University, Hualien, Taiwan
dDepartment of Surgery, Buddhist Tzu Chi General Hospital, Taipei Branch, Taipei, Taiwan
eInstitute of Medical Biotechnology, Central Taiwan University of Science and Technology, Taichung, Taiwan
fInstitute of Microbiology, Immunology and Molecular Medicine, Tzu Chi University, Hualien, Taiwan
Abstract
Objective
Little information is available concerning the relationships between clarithromycin resistance and virulence marker genes (iceA, cagA and vacA) in Helicobacter pylori isolated in Taiwan. The aim of this study was to evaluate the possible association between clarithromycin resistance and genotypes of the virulence markers on clarithromycin-resistant H. pylori isolates obtained in eastern Taiwan
Materials and Methods
The genotypes of the virulence marker genes (iceA, cagA and vacA) were analyzed by PCR, and the 23S rDNA region from 18 clarithromycin-resistant clinical isolates of H. pylori was amplified by PCR and sequenced.
Results
Point mutations were found to occur in all isolates. Two isolates had A2143G, six had T2182C, one had C2227T, six had A2143G plus T2182C, and three had heterozygous alleles. The latter included a wild-type allele (A2143) plus (i) an A2143G, (ii) an A2143G plus an A2223G, and (iii) an A2143G plus a T2182C. The prevalence of the marker genes cagA, iceA1, iceA2, and both iceA1 and iceA2, in the isolates was 95.5%, 66.9%, 7.5%, and 25.6%, respectively. The vacAs1 allele was detected in all isolates, whereas the m1 and m2 alleles were found in 44.4% and 55.6% of the isolates, respectively
Conclusion
There were no significant associations between clarithromycin resistance and the presence of the cagA gene, vacA allele mosaicism, and the iceA genotypes. The most notable finding of our study was that the C2227T single mutation in 23S rDNA could also be related to the high clarithromycin minimal inhibitory concentrations in clinical isolates from eastern Taiwan.
Keywords
Clarithromycin-resistant; Genotyping; Helicobacter pylori; Virulence marker
