Brief Article
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World J Gastroenterol. Feb 28, 2013; 19(8): 1283-1291
Published online Feb 28, 2013. doi: 10.3748/wjg.v19.i8.1283
Ethnicity association of Helicobacter pylori virulence genotype and metronidazole susceptibility
Hanafiah Alfizah, Awang Hamat Rukman, Ahmad Norazah, Razlan Hamizah, Mohamed Ramelah
Hanafiah Alfizah, Department of Medical Medical Microbiology and Immunology, Faculty of Medicine, Universiti Kebangsaan Malaysia Medical Centre, 56000 Cheras, Kuala Lumpur, Malaysia
Awang Hamat Rukman, Department of Medical Microbiology and Parasitology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
Ahmad Norazah, Bacteriology Unit, Institute for Medical Research, Jalan Pahang, 50588 Kuala Lumpur, Malaysia
Razlan Hamizah, Department of Medicine, Faculty of Medicine, Universiti Kebangsaan Malaysia Medical Centre, 56000 Cheras, Kuala Lumpur, Malaysia
Mohamed Ramelah, Centre for Innovative Collaboration, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia
Author contributions: All authors contributed equally in this study.
Supported by Grant from the Ministry of Science, Technology and Innovation, Malaysia, No. 06-02-0055-PR0073/05
Correspondence to: Hanafiah Alfizah, PhD, Department of Medical Microbiology and Immunology, Faculty of Medicine, Universiti Kebangsaan Malaysia Medical Centre, Jalan Yaacob Latif, Bandar Tun Razak, 56000 Cheras, Kuala Lumpur, Malaysia. alfizah@ppukm.ukm.edu.my
Telephone: +60-3-91455442 Fax: +60-3-91456671
Received: October 17, 2012
Revised: December 29, 2012
Accepted: January 11, 2013
Published online: February 28, 2013
Abstract

AIM: To characterise the cag pathogenicity island in Helicobacter pylori (H. pylori) isolates by analysing the strains’vacA alleles and metronidazole susceptibilities in light of patient ethnicity and clinical outcome.

METHODS: Ninety-five H. pylori clinical isolates obtained from patients with dyspepsia living in Malaysia were analysed in this study. Six genes in the cagPAI region (cagE, cagM, cagT, cag13, cag10 and cag67) and vacA alleles of the H. pylori isolates were identified by polymerase chain reaction. The isolates’ metronidazole susceptibility was also determined using the E-test method, and the resistant gene was characterised by sequencing.

RESULTS: More than 90% of the tested isolates had at least one gene in the cagPAI region, and cag67 was predominantly detected in the strains isolated from the Chinese patients, compared with the Malay and Indian patients (P < 0.0001). The majority of the isolates (88%) exhibited partial deletion (rearrangement) in the cagPAI region, with nineteen different patterns observed. Strains with intact or deleted cagPAI regions were detected in 3.2% and 8.4% of isolates, respectively. The prevalence of vacA s1m1 was significantly higher in the Malay and Indian isolates, whereas the isolates from the Chinese patients were predominantly genotyped as vacA s1m2 (P = 0.018). Additionally, the isolates from the Chinese patients were more sensitive to metronidazole than the isolates from the Malay and Indian patients (P = 0.047). Although we attempted to relate the cagPAI genotypes, vacA alleles and metronidazole susceptibilities to disease outcome, no association was observed. The vacA alleles were distributed evenly among the strains with intact, partially deleted or deleted cagPAI regions. Interestingly, the strains exhibiting an intact cagPAI region were sensitive to metronidazole, whereas the strains with a deleted cagPAI were more resistant.

CONCLUSION: Successful colonisation by different H. pylori genotypes is dependent on the host’s genetic makeup and may play an important role in the clinical outcome.

Keywords: Helicobacter pylori, cag pathogenicity island, vacA alleles, Metronidazole susceptibility