Identification des souches de Helicobacter pylori par l’utilisation des marqueurs génétiques.

Abstract

Helicobacter pylori is a pathogen that colonizes the gastric mucosa of-half of the world’s population. This bacterium is responsible for most gastroduodenal diseases such as gastritis,peptic ulcer, adenocarcinoma and gastric MALT lymphoma. The objectives: To provide data about the local epidemiology of H. pylori infection for the first time in Constantine and to contribute ameliorating the management of H. pylori infections. Materials and Methods: We conducted a prospective study achieved between 2013 and 2015, it included 135 adult patients addresses for digestive endoscopy and previously untreated for H. pylori infection. Strains identification was performed by culture and real-time PCR for detection of H. pylori and mutations of its resistance to clarithromycin .The detection of mutations related to resistance to tetracycline and levofloxacin was performed by sequencing. Genotyping of cagPAI, vacAs/m/i pathogenicity factors was achieved by standard PCR. Results: Prevalence of H. pylori infection evaluated by PCR 63.7%, positive culture 17%, primary resistance to clarithromycin due to mutation type A2142/43G is detected with a rate of 18.6%, the Resistance to levofloxacin is due to single mutations Asn87Lys-Asp91GlyAsn87Ile and the double mutation Asn87Lys and Asp91Tyr with a rate of 6%. A single resistance to tetracycline mutation (TGA)(1.2%) was detected. The detection of the pathogenicity genes revealed: cagPAI+ 47%, cagAP1P2P3 58%, vacAs1m120%, vacA s1m2 24%, vacAs2m2 55%.Génotype predominance cagPAI-, vacAs2m2. Conclusion: A high prevalence of H. pylori infection has been detected in Constantine, an adaptation of eradication treatment is necessary following the increase in the rate of resistance to clarithromycin by including other antibiotics. A predominance of less virulent genotype was detected in isolated strains.