Molecular Assessment of Resistance to Clarithromycin in Strains Isolated from Patients with Dyspepsia by Fluorescent In Situ Hybridization in the Center of Iran.

BACKGROUND AND AIMS

is a common infectious bacterium mostly found in gastroduodenal diseases. The increased prevalence of clarithromycin-resistant strains is a major challenge in the successful treatment of infections caused by this organism. The present study is aimed at detecting the clarithromycin resistance pattern of strains isolated from gastric biopsies and evaluating point mutations of the 23S rRNA gene. . In the present descriptive cross-sectional study, 165 patients with gastrointestinal disorders, who were referred to the Endoscopy Center of Dr. Shariati Hospital of Isfahan, Iran, were enrolled from April to July 2018. infection was diagnosed by culture, and susceptibility of the isolates to clarithromycin was assessed by the E-test. Minimum inhibitory concentration (MIC) values were obtained based on EUCAST recommendations. Also, fluorescence in situ hybridization (FISH) was used to determine point mutations associated with clarithromycin resistance.

RESULTS

By using culturing, was isolated from 50.3% (83/165) gastric biopsy specimens. The overall frequency of resistance to clarithromycin was 25.3% (21/83) by the E-test. In the resistance genotypic analysis, 19 isolates had mutations. The prevalence of A2143G and A2144G mutations was 68.4% (13/19) and 31.5% (6/19), respectively. A2143C mutation was not tracked in any isolate. Two isolates with MIC > 0.5 g/mL had no mutations that could be related to other mechanisms of resistance.

CONCLUSION

As presented in the study, the high prevalence of clarithromycin-resistant due to point mutations of the 23S rRNA gene indicates the necessity of revising the standard treatment regimen based on antibiotic susceptibility pattern of each region.