pylori are closely related to clarithromycin resistance. There was an absolute relation between 23s rRNA gene point mutations and clarithromycin resistance in this study. Helicbacter pylori resistance to clarithromycin can cause failure in the eradications of the bacteria. The resistance of the bacteria is expanding in most parts of the world including Iran. Key Words:

Clarithromycin, point mutations, Helicobacter pylori Introduction Helicobacter pylori is a microaerophilic gram-negative organism involved in many digestive system diseases, Inhibitors,research,lifescience,medical such as peptic ulcer, gastritis, or mucosa-associated lymphoid tissue (MALT) lymphoma, or acting as a risk factor in the development of gastric cancer.1 The prevalence of H. pylori infection varies greatly among different countries, as in many developing countries it is over 70%, while in most industrialized nations it is 20% to 50%.2 Eradication of H. pylori is an important component of treatments for peptic ulcer disease and other gastrointestinal disorders.3Triple or quadruple Inhibitors,research,lifescience,medical therapy regimen containing a proton-pump inhibitor (PPI) and antibiotics, mainly clarithromycin and metronidazole, are currently in use.4 The inhibition of protein synthesis is the functional mechanisms of the macrolides, causing the separation of Inhibitors,research,lifescience,medical peptidyl-tRNA from the ribosome during the elongation reaction.5 One of the most common components of the H. pylori infections

therapy regimens is clarithromycin. The resistance to EGFR activation macrolides such as clarithromycin in

H. pylori has been demonstrated to occur at different rates (1 to 10%) in different countries, and is an important cause of H. pylori therapeutics regimens failure. Furthermore, macrolide-resistant Inhibitors,research,lifescience,medical H. pylori mutants are simply obtained by in vitro selection.5 Macrolide resistance is caused by Inhibitors,research,lifescience,medical several mechanisms such as the lack of macrolide binding to the ribosomal target, inactivation of the macrolides by enzymes, reduced or lack of bacterial membrane permeability, and macrolides active efflux.5 The widespread use of clarithromycin for the treatment of H. pylori infection has resulted in the development of resistance.6 Clarithromycin resistance (ClaR) of H. pylori is mainly caused by point mutations of the genomic ADP ribosylation factor 23s rRNA, the main component of the 50S subunit, mostly at position 2142/43 (A2142 to G/C/T; A2143 to G/C) in the peptidyl-transferase region of the V domain, thereby preventing drug binding. ClaR is increasing due to widespread use of macrolides for other diseases in the western world.7 There are some methods to detect the point mutations in genes such as sequencing, and amplification and restriction fragment length polymorphism (RFLP). In this study we used the RFLP method to detect the point mutations in 23s rRNA gene in our local H. pylori isolates.8 Clarithromycin is recognized as the key antibiotic for the treatment of H. pylori infections, as has a powerful bactericidal effect in vitro compared with the other available macrolides.