Helicobacter pylori in children: acquisition of antimicrobial resistance after an initial course of treatment.

According to a recent consensus statement concerning Helicobacter pylori infection in children (3), upper gastrointestinal endoscopy with biopsies is the preferred method for establishing an etiologic diagnosis of infection. The treatment recently recommended for children combines a gastric acid inhibitor, usually a proton pump inhibitor (PPI), with two antimicrobial agents, an antimicrobial agent plus a bismuth salt, or two antimicrobial agents (4). In France, where the use of bismuth salts is not authorized, treatment consists of amoxicillin plus either clarithromycin or metronidazole. The consensus statement (3) also proposed a strategy for reevaluating those who remain infected after an initial course of therapy: repeat endoscopy with culture and antimicrobial susceptibility testing, with secondary treatment based on susceptibility test results. We have already shown that the rates of resistance to metronidazole and clarithromycin among isolates of H. pylori from children are high before treatment (i.e., 43 and 21%, respectively) (5). No data are available concerning the antimicrobial susceptibility patterns of strains obtained from cultures from children who had failed an initial course of therapy. The aim of this study was to assess antimicrobial resistance rates in H. pylori strains after an initial course of treatment. During the period from 1993 to 2000, 15 girls and 8 boys (mean age 6 standard deviation, 10.9 1/2 4.8 years; range, 1.4 to 17 years) with culture-confirmed H. pylori gastritis failed to respond to an initial course of therapy (1 week of treatment with a PPI and amoxicillin together with either clarithromycin [n 5 14] or metronidazole [n 5 9]). Six weeks after the end of treatment, the [C]urea breath test was performed on all patients. If a positive result was obtained, a second endoscopy was performed and gastric biopsy samples were obtained for culture and antimicrobial susceptibility testing. Biopsies were performed prior to initiating a second course of treatment. Clarithromycin-resistant strains of H. pylori were recovered from 8 children (34.7%) prior to the initial course of treatment and from 12 children (52.1%) after treatment (difference not significant); metronidazole-resistant isolates were obtained from 13 children before treatment (56.5%) and from 12 children after treatment (52.1%) (difference not significant); and isolates resistant to both clarithromycin and metronidazole were obtained from 4 children before treatment (17.3%) and from 7 children after treatment (30.4%) (difference not significant). All strains remained susceptible to amoxicillin (Table 1). Resistance to clarithromycin was noted among posttreat-