Sensitivity to nitazoxanide among metronidazole resistant Helicobacter pylori strains in patients with gastritis

Background: In this study, the efficacy of nitazoxanide in the treatment of Helicobacter pylori isolates, which were resistant to metronidazole, was examined. Methods: One hundred twenty two patients who underwent endoscopy examinations at Kasra and Laleh hospitals in Tehran from November 2014 to July 2015 were enrolled. Helicobacter pylori strains were isolated from the patients’ endoscopy biopsies by bacteriological culture. Those bacterial isolates resistant to metronidazole were examined for susceptibility to nitazoxanide. Serial agar dilution method was utilized to determine the minimum inhibitory concentrations for the antibiotics. Results: From 122 gastric biopsy specimens, 55 H. pylori isolates were recovered (45%); of which, 40 (72.7%) were resistant to metronidazole. Comparing the MIC values of nitazoxanide with metronidazole revealed significant differences (p<0.05). The MIC(50) and MIC(90) values for nitazoxanide and metronidazole were 8 and ≥8μg/ml, and 32 and 64μg/ml, respectively. Conclusion: The high levels of metronidazole resistance suggest that this medication may not be beneficial for first-line therapy in Iran. However, considering the relative effectiveness of nitazoxanide, it may be considered a suitable alternative for patients in Iran.