Metronidazole resistance and virulence factors in Helicobacter pylori as markers for treatment failure in a paediatric population

The eradication rate obtained using the classical triple therapy containing metronidazole, amoxicillin and bismuth citrate, was determined in 57. paed iatric patients with digestive disorders, according to the susceptibility t o metronidazole of the Helicobacter pylori strains (determined by agar dilu tion) and the cagA and vacA status (determined by PCR). Eradication was obt ained in 38 out of 43 patients (85.3%) infected by H. pylori with metronida zole MIC less than or equal to 2 mg l(-1), in 3 out of 6 patients (50%) whe n MIC was 4-8 mg l(-1) and in 4 out of 8 patients (50%) when MIC was > 8 mg l(-1). Among patients infected with cagA+ and cagA - strains an eradicatio n rate of 75% (6/8) and 75% (18/24) was found, and 50% (3/6) and 80% (21/26 ) among vacA s1- and vacA s2-infected subjects (P > 0.05). H. pylori eradic ation depends on the susceptibility of the strain to metronidazole, being h igher in patients infected with susceptible H. pylori. However, according t o our data the cagA or vacA status was not an important factor in treatment failure in the eradication of H. pylori. (C) 1999 Federation of European M icrobiological Societies. Published by Elsevier Science B.V. All rights res erved.