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Primary and secondary resistance to metronidazole and clarithromycin in Spanish Helicobacter pylori clinical isolates obtained from children

Abstract number: 1733_428

Cibrelus L., Alarcon T., Urruzuno P., Martinez M., Perez De Ayala A., Diaz-Regañon J., Lopez-Brea M.

Objective: To determine the primary and secondary resistance to metronidazole and clarithromycin in Spanish Helicobacter pylori (HP) clinical isolates obtained from paediatric patients from January 2002 to June 2006.

Methods: Samples were collected from gastric biopsies of symptomatic paediatric patients and H. pylori cultured as previously described. Resistance was determined by E-test. Strains were considered resistant if MIC ≥ 2 mg/l for amoxicillin, ≥4 mg/l for tetracyclin, ≥8 mg/l for metronidazole and ≥1 mg/l for clarithromycin and intermediate if MIC = 0.5 mg/l for clarithromycin, Medical record were retrospectively reviewed to get histories. Statistical analysis was based on chi2 tests using Stata software. Significance was construed for p < 0.05.

Results: 101 patients were included: 38 males and 63 females (gender ratio M/F = 0.6). They were aged 10 years in average (standard deviation 3.3, ranges 4–18 years). Thirty-five patients (34.7%) had history of treatment failure, and were therefore considered as secondary HP-infection, with no statistical difference in distribution of gender (0.5 M/F ratio for patients with history of treatment failure versus 0.7 without, p = 0.61) or class breaks of age (45.7% (n = 16) over 12 among patients with history of treatment failure versus 27.0% (n = 17) without, p = 0.06).

All strains were susceptible to amoxicillin and tetracycline, 35.7% (n = 35) were resistant to metronidazole, 54.6% (n = 54) to clarithromycin and 2.0% (n = 2) were intermediate to clarithromycin. Double resistance to metronidazole and clarithromycin rated to 17.2% (n = 17). Primary and secondary resistance rates to metronidazole and clarithromycin (including double resistance) are detailed in the table.

AntibioticPrimary resistancea, n (%)Secondary resistancea, n (%)RRbp
Metronidazole21 (32.8%)14 (41.2%)1.30.41
Clarithromycin32 (49.2%)24 (70.6%)1.40.04
Double resistance10 (15.4%)9 (26.5%)1.70.18
aIntermediate strains to clarithromycin were considered as resistant.bRR of resistance in case of treatment failure.

Conclusion: Resistance to clarithromycin (56.6%) was higher than to metronidzole (35.7%) in the HP strains studied herein. Clarithromycin resistance was very high even in strains from paediatric patients not previously treated for HP infection (49.2%).

Acknowledgement: The study was supported by FIS PI 052452.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Subject:
Location: ICC, Munich, Germany
Presentation type:
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