Antimicrobial susceptibility test of Helicobacter pylori isolated from Jos, Nigeria

Fifty-five strains of Helicobacter pylori isolated from November 1997 until October 1998 from 33 female and 22 male adults attending for endoscopy at the Evangel Hospital, Jos, Nigeria were assayed for antibiotic susceptibility to amoxycillin, clarithromycin, metronidazole and tetracycline by the E-test strip method. Minimum inhibitory concentration (MIC) within the attainable peak serum concentrations for each drug was used as the parameter to determine the susceptibility of H. pylori. The results showed 100% susceptibility for amoxycillin, 89.0% for tetracycline, 87.3% for clarithromycin and 60% for metronidazole. The MIC50 and MIC90 values were: 0.016 microgram/mL and 0.75 microgram/mL for amoxycillin, 0.016 microgram/mL and 2 micrograms/mL for clarithromycin, 0.094 microgram/mL and 12 micrograms/mL for tetracycline, and 2 micrograms/mL and > 48 micrograms/mL for metronidazole. The MIC90 values for metronidazole (> 48 micrograms/mL) and tetracycline (12 micrograms/mL) were in each case higher than the break-point value (peak serum concentrations) of 8 micrograms/mL for metronidazole and 3 micrograms/mL for tetracycline. This pattern of resistance to metronidazole and tetracycline has to be considered when therapeutic regimens against H. pylori contain either or both drugs.