Rev Esp Quimioter 2009:22(2):88-92

High percentage of clarithromycin and metronidazole resistance in Helicobacter pylori clinical isolates obtained from Spanish children

S. Agudo ,  T. Alarcón ,  L. Cibrelus ,  P. Urruzuno ,  M. J. Martínez y M. López-Brea 


Objective.To determine the primary and secondary resistance to several antimicrobial agents in Spanish Helicobacter pylori 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 according to standard microbiological procedures. Resistance was determined by E-test. Strains were considered resistant if minimal inhibitory concentration (MIC) ≥ 2 mg/l for amoxycillin, ≥4 mg/l for tetracycline, ≥ 8 mg/l for metronidazole, ≥ 1 mg/l for clarithromycin, MIC ≥ 4 mg/l for ciprofloxacin, MIC  ≥32 mg/l for rifampicin and intermediate if MIC = 0.5 mg/l for clarithromycin, and MIC = 2 mg/l for ciprofloxacin.

Results. A total of 101 patients were included: 38 males and 63 females (sex ratio M/F: 0.6). Average age was 10 years (range: 4-18 years). All strains were susceptible to amoxycillin, tetracycline and rifampicin, 35.7% were resistant to metronidazole, 54.6% to clarithromycin and 1.8% to ciprofloxacin. 2.0% were intermediate to clarithromycin and 1.8% to ciprofloxacin. Double resistance to metronidazole and clarithromycin rated at 17.2%. Thirty-five patients (34.7%) had a history of treatment failure, and were considered as secondary H. pylori. Primary resistance rates to metronidazole and clarithromycin were 32.8% and 49.2%, respectively, and secondary resistance rates were 41.2% and 70.6%, respectively.

Conclusions. Resistance to clarithromycin (56.6%) was higher than to metronidazole (35.7%) in the H. pylori strains studied. Clarithromycin resistance was very high even in strains from paediatric patients not previously treated for H. pylori infection.


Keywords: Primary resistance. Paediatrics. Ciprofloxacin. Rifampicin. Treatment failure.

Rev Esp Quimioter 2009:22(2):88-92 [pdf]