Evaluation of INNO-LiPA mycobacteria v2 assay for identification of rapidly growing mycobacteria

A total of 54 rapidly growing mycobacteria (RGM) isolated from patients attended in the two hospitals of Cádiz Bay (Spain) were selected during a seven-year-period (2000-2006) in order to evaluate the INNO-LiPA Mycobacteria v2 assay for mycobacterial identification, based on the reverse hybridization principle. The strains were cultured in Löwenstein-Jensen and Middlebrook 7H9 media and identified to the species level by sequencing of the 16S rRNA, PCR-restriction enzyme analysis of the hsp65 gene, conventional tests and INNO-LiPA Mycobacteria v2 assay. By the molecular methods we identified a total of 12 different species: 23 Mycobacterium fortuitum, 11 M. chelonae, 10 M. abscessus, 2 M. senegalense, 1 M. alvei, 1 M. brumae, 1 M. mageritense, 1 M. mucogenicum, 1 M. neoaurum, 1 M. peregrinum, 1 M. septicum and 1 M. smegmatis. Fifty two strains (96.3%) were correctly identified by conventional techniques and 47 strains (87.0%) by INNO-LiPA Mycobacteria v2 assay. We find INNO-LiPA Mycobacteria v2 assay simple to perform but it provides few advantages in comparison with conventional methods and sometimes needs complementary tests to identify Mycobacterium fortuitum complex, M. chelonae complex and specific species due to the great heterogeneity in the RGM group.