Twelve year observation of primary and secondary antibiotic-resistant Helicobacter pylori strains in children

Background. The effectiveness of Helicobacter pylori eradication regimens i s influenced by an. tibiotic susceptibility of infecting strains. Data conc erning antibiotic resistance in children are limited. We report the evoluti on of primary and secondary resistance in a series of Belgian children duri ng the last 12 years. Patients and methods. From 1989 through 2000, H. pylori gastritis was diagn osed in 569 children, and antibiotic susceptibility tests were performed in 555. Eradication, using different schemes, failed in 128 of 457 treated ch ildren. After eradication failure antibiotic susceptibility determination w as performed in 87 of 128. Comparison of antibiotic susceptibility of strai ns isolated from the gastric body and from the antrum was performed in 238 samples. Results. Resistance to amoxicillin was not observed. The rate of primary re sistance to nitroimidazole derivatives was 18.0% (101 of 555) and remained constant throughout this period, whereas primary resistance to macrolides i ncreased from an average of 6.0% (range, 0 to 10%) before 1995 to 16.6% (ra nge, 10 to 25%, P < 0.001) thereafter. Antibiotic consumption in Belgium, e specially macrolides, did not show important fluctuations during the study period. Secondary resistance developed in 39 of 87 patients (46%). Strains isolated from different gastric locations show identical susceptibility tes ting in all but 5 of 238. Conclusions. Resistance of H. pylori to macrolide s increased in our pediatric population which did not appear to correlate w ith macrolides prescription habits in our country. After eradication failur e acquired secondary resistance was observed in one-half of the patients.