To develop the rapid and simple genomic diagnostic method, we analyzed the partial dnaA sequence of 27 mycobacterial species. The partial dnaA sequence could distinguish M. kansasii and M. gastri. Based on this region and RLEP sequence of M. leprae, we established the loop-mediated isothermal amplification method (LAMP) to detect each species. The LAMP method for M. kansasii and M. gastri, could detect 500 copies. Five copies of M. leprae genomic DNA could be detect in 30min. To simplify the sample processing, the LAMP assay was performed with FTA filter paper. M. leprae bacilli were applied on filter paper that lyses bacilli and bound DNA, eliminating sample centrifugation and extraction procedures. Assays of number standards showed reproducible detection rate 50 bacilli of M. leprae. Thus, The LAMP assay combined with FTA card has the advantages of rapid and simple detection and provides a practical, economical, and specific method for the diagnosis of M. leprae and NTM infection.
