Antibiotic Susceptibility of Helicobacter pylori and the Combination Effect of Antibiotics on the Antibiotic - Resistant H . pylori Strains

ABSTRACT

The purpose of this study was to evaluate the existence of amoxicillin, clarithromycin, and metronidazole resistance Helicobacter pylori and to determine the in-vitro MIC of two and three kinds of antibiotic concominant administration in the isolates. The antimicrobial agents tested against 169 H. pylori included metronidazole, amoxicillin, ciprofloxacin, clarithromycin, omeprazole, josamycin, erythromycin, and tetracycline. MIC of each antimicrobial agents was determined by broth microdilution method. The 169 strains of H. pylori were isolated from biopsy specimens of patients with gastric cancer. MIC50 of clarithromycin, amoxicillin, metronidazole, omeprazole, erythromycin, josamycin, tetracycline, and ciprofloxacin was 2.0, 1.0, 4.0, 8.0, 0.5, 0.5, and 0.5 ug/ml, respectively. MIC90 of clarithromycin, amoxicillin, metronidazole, omeprazole, erythromycin, josamycin, tetracycline, and ciprofloxacin was 64.0, 64,0, 32.0, 16.0, 8.0, 2.0, and 1.0 ug/ml, respectively. H. pylori isolates were detected in the following resistaince rates 34.3% to clarithromycin, 31.9% to metronidazole, 20.7% to amoxicillin, 12.4% to erythromycin, and 10,1% to josamycin. The prevalence of the antibiotic resistant strains of H. pylori were detected 18.1% for two kind of antibiotics and 9.6% for three kind of antibiotics, and 3.9% for four kind of antibiotics. The MIC90 of clarithromycin-, metronidazole-,and amoxicillin-resistant H. pylori was decreased under the 1 ug/ ml by the two or three kind of antibiotic concomitant administration in-vitro. These results suggest that two or three antibiotics concomitant administration could be more effective for the treatment of clarithromycin-, amoxicillin-, metronidazole-, and josamycin-resistant H. pylori strains.