METRONIDAZOLE-RESISTANT AND CLARITHROMYCIN-RESISTANT HELICOBACTER-PYLORI IN DYSPEPTIC PATIENTS IN WESTERN SYDNEY AS DETERMINED BY TESTING MULTIPLE ISOLATES FROM DIFFERENT GASTRIC SITES

It is unknown whether antibiotic susceptibility resting of antral isol ates alone is representative of Helicobacter pylori susceptibility. We aimed to determine: (i) the prevalence of metronidazole- and clarithr omycin-resistant strains in infected dyspeptic patients; and (ii) whet her there is consistency in the susceptibility to metronidazole and cl arithromycin among isolates cultured from different gastric sites. Ant ral, body and fundus biopsies were taken from 242 consecutive patients and cultured on blood agar under micro-aerophilic conditions for 5-7 days. Isolates from 66 patients (13 had one, 15 had two and 38 had thr ee isolates) were tested for susceptibility to metronidazole and clari thromycin using previously validated disc diffusion tests. Of the 66 p atients, 42 (64%) had strains resistant to metronidazole while four (6 .1%) had clarithromycin-resistant strains. The prevalence of metronida zole resistance was not significantly different between men and Ls ome n (65% vs 60%) or across different age groups. In five (9.4%) of the 5 3 patients with multiple isolates, discrepant results for metronidazol e susceptibility were observed: susceptible antral and body isolates b ut resistant fundus isolates in two cases and susceptible antral isola tes but resistant body and fundus isolates in the others. Clarithromyc in susceptibilities were consistent among the isolates cultured from d ifferent gastric sites in all patients. It is concluded that metronida zole-resistant: strains of H. pylori are common while clarithromycin-r esistant strains are rare. Metronidazole susceptibility resting of ant ral isolates does not appear to be representative of isolates from the body and fundus in a subset of patients.