Molecular characterization of nitroimidazole resistance in metronidazole-resistant bacteroides species isolated from hospital patients in Kuwait

Abstract

Objectives: The aim of this study was to screen for infections caused by metronidazole (MTZ)-resistant Bacteroides spp., and to characterize the genes that encode the MTZ resistance.

Materials and methods: A total of 7 MTZ-resistant Bacteroides spp. were isolated from 5 patients with MTZ-resistant infections. These organisms were investigated for carriage of genes that encode MTZ resistance. The presence of these genes was investigated by PCR and the PCR products were subjected to PCR-RFLP analysis.

Results: The strains were MTZ-resistant with minimum inhibitory concentrations of > 32 microg/ml. The presence of nim genes was indicated by PCR in all 7 strains. PCR-RFLP analysis of the nim gene products demonstrated two of the five reported resistance genes, nimA-nimE. These two resistance genes were nimE in 5 of the 7 isolates and nimA in 2 strains.

Conclusion: MTZ-resistant Bacteroides spp. have been isolated from patients in Kuwait. Nim genes, specifically nimE and nimA, mediate the drug resistance in these isolates. The methods used in detecting these genes are rapid, accurate and relatively inexpensive and could be adopted easily to help in monitoring emergence of MTZ resistance determinants in Kuwait.