A 9 year study of clarithromycin and metronidazole resistance in Helicobacter pylori from Spanish children.

The evolution of clarithromycin, metronidazole and amoxycillin resistance in 246 Spanish Helicobacter pylori clinical isolates, obtained from paediatric patients during a 9 year period, was determined by an agar dilution technique. Clarithromycin resistance (MIC 1 mg/L) was 2.27% (IC95 0.05-12.02) in 1991-1993, 20.98% (IC95 12.72-31.46) in 1994-1996 and 28.33% (IC95 20.48-37.28) in 1997-1999 (P < 0.01). Metronidazole resistance (MIC 8 mg/L) was 7.14% (IC95 1.49-19.48) in 1991-1993, 20.25% (IC95 12.04-30.79) in 1994-1996 and 43.90% (IC95 32.95-55.30) in 1997-1999 (P < 0.01). Amoxycillin resistance was not found (all strains showed MICs < 2 mg/L).