RESUMEN
Clarithromycin resistance in Helicbacter pylori has been found to be associated with point mutations in 23s rRNA gene leads to reduced affinity of the antibiotic to its ribosomal target or changing the site of methylation. The aim of this study was to determine the most important point mutations in 23s rRNA gene in H. pylori that are closely related to clarithromycin resistance among such isolates. Sixty three H. pylori isolates, obtained from gastric biopsy speciemens in Kerman, Iran, were used to evaluate their susceptibility to clarithromycin by disk diffusion test, and to detect the most common point mutations in 23s rRNA gene associated with clarithromycin resistance by Polymerase chain reaction-amplification and restriction fragment length polymorphism [PCR-RFLP] and 3'-mismatch PCR. 31.7% of the H. pylori isolates were resistant to clarithromycin, and each of the resistant isolate had at least one of the most common point mutations in 23s rRNA gene associated with calrithromycin resistance. According to our results three common point mutation in 23s rRNA gene in H. 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