Rapid detection of ermB gene in Clostridium difficile by loop-mediated isothermal amplification.

Macrolide-lincosamide-streptogramin B resistance in Clostridium difficile is mostly due to the ermB resistance determinant. Here, we describe a sensitive and rapid molecular method to detect ermB in C. difficile to contribute to the wider epidemiological study. Five sets of loop-mediated isothermal amplification (LAMP) primers were designed and optimized for rapid detection of ermB. The specificity and sensitivity of the primers for ermB were detected, and the ermB LAMP assay was compared to conventional PCR with 80 clinical isolates of C. difficile. Real-time monitoring of turbidity and chromogenic reaction were used to determine negative and positive results. A total of 26 pathogenic bacterial strains of different species were found to be negative for ermB, which indicated the high specificity of the primers. ermB was detected in 78.8 % (63/80) of the clinical isolates by both LAMP and conventional PCR. The detection limit of LAMP was 36.1 pg DNA mu l(-1) and its sensitivity was 10-fold greater than that of conventional PCR. This study is the first report regarding the development and application of the LAMP assay for detection of the ermB gene in C. difficile strains. The developed LAMP method is sensitive, specific and provides a user-friendly visual approach for the rapid detection of ermB-bearing C. difficile.