Resistance Rate and Minimum Inhibitory Concentration of Metronidazole Among Helicobacter pylori Strains in Tehran, Iran

Background: Constant monitoring of Helicobacter pylori resistance is necessary for selection of the best treatment regimen for eradication of the resistant strains. Objectives: The aim of this study was to investigate diversity of resistance and minimum inhibitory concentration (MIC) of H. pylori strains against metronidazole in Tehran, Iran. Patients and Methods: This cross-sectional study was performed among 96 patients, who had undergone gastric endoscopy at Imam Khomeini hospital in Tehran, during years 2013 to 2014. Helicobacter pylori isolates were obtained from gastric biopsy samples on selective culture media after characterization by conventional biochemical tests and polymerase chain reaction. Minimum inhibitory concentration of metronidazole was determined by the agar dilution method. Results: Helicobacter pylori infection was detected in 22 patients (22.92%). Identity of the isolates was confirmed by PCR using glmM primers. Chronic gastritis, duodenitis, intestinal metaplasia, dysplasia and cancer were detected among 70.1%, 6.25%, 1.04%, 1.4% and 10.41% of the patients, respectively. Smoking showed a negative relationship with H. pylori infection. The rate of antibiotic resistance was 81.8% (18/22) and MIC ranges of 8 to 512 mu g/mL were detected. Furthermore, MIC50 and MIC90 were determined as 256 and 512 mu g/mL, respectively. Conclusions: In conclusion, these results suggested a need for a switch to second line therapy regimens for treatment of infected patients in the Iranian population.