Infection with Helicobacter pylori: Prevalence, research and impact of antibiotic resistance

tance to metronidazole was 15-40% in Europe, 20-35% in the United States, 76% in Mexico, 53% in Brazil, 9-12% in Japan and 40% in Korea, while that of resistance to amoxicillin and tetracyclines was below 1% A meta-analysis of 20 clinical trials in the USA acknowledges an increased prevalence of resistance to clarithromycin, from 4.9% in 1993-95 to 10.1% in 1995-99 (38). A multicenter European study with homogeneous methodology performed in 22 countries during 1998 found that the prevalence of primary resistance to clarithromycin was 9.9%, to metronidazole was 33.1%, and to amoxicillin was 0.8%. Resistance to clarithromycin was more common in children versus adults, and in southern (18%) versus central (9.3%) or northern (4.2%) European countries. Simultaneous resistance to clarithromycin and metronidazole was also more frequent in southern European countries