Abstract

The present study investigated the in vitro inhibiting and eradicating effect ofHelicobacter hepaticus (Hh) by various antibiotics, and analyzed the inhibiting effect of the combined application of single-drug sensitive antibiotics to Hh. E-test method and Kirby-Bauer disk agar diffusion method were used to detect the minimum inhibitory concentration (MIC) and inhibition zone diameter of a standard Hh strain (ATCC51449, American Type Culture Collection) and an isolate, respectively. Then the checkerboard dilution method was used to determine the fractional inhibitory concentration (FIC) and the combined sensitivity effect. Hh standard strain ATCC51449 and the isolate were highly sensitive to levofloxacin, moxifloxacin and meropenem; sensitive to amoxicillin, ofloxacin, clarithromycin, tinidazole, metronidazole and tetracycline; whereas not sensitive to the cephalosporins and glycopeptide antibiotics. Amoxicillin combined with metronidazole, clarithromycin, levofloxacin, or tetracycline (FIC index <0.5) showed synergistic inhibitory effect; clarithromycin combined with piperacillin tazobactam, metronidazole meropenem, metronidazole piperacillin tazobactam and meropenem combined with piperacillin tazobactam showed cumulative effect (FIC index from 0.5 to 1). In contrast, amoxicillin combined with piperacillin-tazobactam, as well as tetracycline combined with piperacillin tazobactam showed an independant effect (FIC index from 1 to 2). Single meropenem and combination of ofloxacin and amoxicillin are the best antibiotic and antibiotic combination respectively for inhibiting the growth of Hh. These findings are expected to provide an experimental basis for further screening of the antibioticssensitive to Hh for future clinical eradication of Hh and avoiding resistance at maximum limit.

Key words: Helicobacter hepaticus, inhibitory effect, sensitivity, antibiotics.