ANTIMICROBIAL RESISTANCE IN ISOLATES OF H ELICOBACTER-PYLORI IN A REFERRAL CENTER

Objective. To estimate the frequency of H. pylori clinical isolates re sistant to six commonly used antimicrobials. Design. Cross-sectional o bservational study. Setting. A tertiary-referral health care instituti on in Mexico City. Participants. 31 isolates of H. pylori from 31 pati ents with chronic antral gastritis were obtained from gastric mucosal biopsy specimens. Main outcome measure. The Minimum Inhibitory Concent ration (MIC) to ampicillin, amoxycillin, tetracycline, doxycycline, me tronidazole and to colloidal bismuth subcitrate was determined by the agar plate dilution test. Results. All isolates showed to be susceptib le to the former four antibiotics but only in 46% and 55% growth was i nhibited by 8 mu g/mL and 16 mu g/mL of metronidazole, respectively. A ll isolates were inhibited by less than or equal to 128 mu g/mL of bis muth. A 50% increase in the percentage of metronidazole-resistant isol ates (MIC greater than or equal to mu g/mL) between 1988 to 1992 was o bserved. Conclusion. There is a need of future studies in our setting aimed at assessing the cost/effectiveness of diverse H. pylori-associa ted peptic ulcer treatment options.