Comparative Evaluation of Disk Diffusion and E-Test in Determining the Susceptibility of Helicobacter Pylori to Metronidazole, Clarithromycin and Amoxicillin

Document Type : Original Article (s)

Authors

1 MSc Student, Department of Microbiology, School of Medicine AND Student Research Committee, Isfahan University of Medical Sciences, Isfahan, Iran

2 Associate Professor, Department of Microbiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran

3 Instructor, Department of Microbiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran

4 Professor, Department of Gastroenterology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran

5 Associate Professor, Department of Bacteriology and Virology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran

Abstract

Background: Increasing prevalence of antibiotic-resistant Helicobacter pylori strains have severe consequences. It is also the most important factor in determining the outcome of treatment with antibiotics. Therefore, using reliable, easy, fast, and inexpensive methods to determine of antibiotic susceptibility is crucial. Currently, there is no standard recommended for testing these fastidious organisms and interpretive criteria for determining the susceptibility or resistance of bacteria is not yet standardized. Among conventional methods to assess antibiotic susceptibility of bacteria are modified disk diffusion method (MDDM) and E-test. The aim of this study was to compare the results of MDDM and E-test in determining the susceptibility of Helicobacter pylori to metronidazole, clarithromycin, and amoxicillin. Methods: We collected 30 Helicobacter pylori isolates from biopsy specimens. MDDM and E-test were then used to detect the susceptibility of the isolates to metronidazole, clarithromycin, and amoxicillin. The results were compared according to the Clinical and Laboratory Standards Institute protocols. Findings: In both MDDM and E-test, Helicobacter pylori resistance to metronidazole, clarithromycin, and amoxicillin was 53.3%, 16.6%, and 10.0%, respectively. In addition, the minimum inhibitory concentration was determined for isolates resistant to three antibiotics. Conclusion: MDDM and E-test had similar results regarding the susceptibility of Helicobacter pylori to metronidazole, clarithromycin, and amoxicillin. Thus, for determination of antibiotic resistance of Helicobacter pylori isolates, disk diffusion method could be replaced with E-test. Keywords: Helicobacter pylori, Antibiotic resistance, Modified disk diffusion method, E-test