Development and evaluation of novel loop-mediated isothermal amplification for rapid detection of bla(IMP-1) and bla(VIM-2) genes

Loop-mediated isothermal amplification (LAMP) amplifies a target gene with high specificity and rapidity under isothermal conditions. LAMP assays were developed for the rapid detection of metallo-beta-lactamase (MBL) genes such as bla(IMP-1)) and bla(VIM-2). We initially designed specific primers to detect MBL genes for LAMP assays and evaluated the specificity and sensitivity of these assays. LAMP assays amplified MBL genes under a constant temperature of 63 degrees C within 1 hour, and were compared to PCR in MBL-producing strains. The results of MBL genes typing by LAMP assays agree completely with PCR results. The lower detection limits of bla(IMP-1)- and bla(VIM-2)-LAMP assays using real-time turbidimeters were 30cfu/test and 3cfu/test. After amplification, products were directly observed by the naked eye with a fluorescent detection reagent. In conclusion, LAMP assays are convenient, rapid, and fully feasible for detecting MBL genes in ordinary clinical microbiology laboratories without special apparatus.