Prevalence and characteristics of nim genes encoding 5-nitroimidazole resistance among Bacteroides strains isolated in Morocco

We report here an evaluation of the dissemination of nim genes, encoding 5- nitroimidazoles resistance, among Bacteroides clinical strains isolated in Morocco. This study was done using a PCR method. Among 60 strains studied, nine contain a copy of a nim gene, The sequence determination of these gene s showed that they are homologous to three nim genes previously characteriz ed in strains isolated in France: nimB (five genes), nimC (three genes), an d nimA tone gene). Although the nimA and nimC genes were previously identif ied on plasmids pIP417 and pIP419, respectively, we found here that they ha ve a chromosomal location. The MICs of three 5-nitroimidazole antibiotics ( metronidazole, ornidazole, and tinidazole) of the nim gene-containing strai ns were very low (0.5-2 mug/ml), indicating that the nim genes were not eff iciently expressed in these clinical isolates.