Risk factors for primary Helicobacter pylori resistance in Bulgarian children.

Risk factors for primary Helicobacter pylori resistance in 186 children with gastroduodenal diseases (44 from villages/small towns and 130 from large towns/cities) in 2000-2003 were tested. Susceptibility was tested by a limited agar dilution method. Overall resistance rates to metronidazole, clarithromycin, tetracycline and both metronidazole and clarithromycin were 14.5, 11.9, 3.3 and 4.3 %, respectively. No amoxycillin resistance was observed. Tetracycline resistance was found in six children aged 7-18 years. Clarithromycin resistance was more common in children from small towns/villages (22.7 %) than in those from large towns/cities (8.5 %, P < 0.05). There were no significant differences (P > 0.05) in resistance rates between children from northern Bulgaria and those from southern regions. Resistance rates in duodenal ulcer patients and other children were, respectively, 10.5 and 15 % (P > 0.20) for metronidazole and 10.5 and 12 % (P > 0.20) for clarithromycin. No combined resistance to metronidazole and clarithromycin was found in 22 children aged 1-7 years and in 34 children living in northern Bulgaria. There were no significant associations of resistance with sex and age group (1-7- versus 8-18-year-old children) for all antibacterial agents tested. In conclusion, primary H. pylori resistance was absent (for metronidazole + clarithromycin) or low (4.5 % for clarithromycin) in children aged 1-7 years. Place of residence was associated with clarithromycin resistance rates.

Prevalence of resistant Helicobacter pylori isolates in Bulgarian children.

The aim of this study was to assess the primary and combined resistances of Helicobacter pylori isolates obtained from paediatric patients in 2000-2001 to seven antimicrobial agents. Resistance rates of pre-treatment isolates from 115 children were investigated by the limited agar dilution method alone and by the E-test. The cut-off concentrations for resistance were: metronidazole >8 mg/L, clarithromycin and azithromycin >1 mg/L, clindamycin >4 mg/L, amoxicillin >0.5 mg/L, tetracycline >4 mg/L and ciprofloxacin >1 mg/L. Primary resistance rates were: metronidazole 15.8%, clarithromycin 12.4%, azithromycin 14.6%, clindamycin 20.0%, amoxicillin 0%, metronidazole + clarithromycin 4.5%, ciprofloxacin 6.0%, metronidazole + clarithromycin + ciprofloxacin 1.2%, tetracycline 3.1% and metronidazole + ciprofloxacin 1.2%. There were no significant age (1-9 years versus 10-18 years) or gender differences. Prevalence of both macrolide-resistant and intermediately susceptible strains was 21.9% for azithromycin and 15.9% for clarithromycin. Of 18 metronidazole-resistant isolates, 77.8% exhibited a metronidazole MIC > or = 32 mg/L. H. pylori resistance rates to metronidazole, clarithromycin and both agents were relatively low in Bulgarian children. However, resistance was found to all drugs tested except for amoxicillin. The consumption of newer macrolides and tetracyclines could be related to the prevalence of resistance to the corresponding agents. There were no significant differences in primary resistance rates of H. pylori to antimicrobial agents between children and adults except for metronidazole. Multi-drug resistance to newer macrolides, metronidazole and ciprofloxacin in association with a slightly elevated amoxicillin MIC (0.38 mg/L) was detected in one strain.