Rapid differentiation between clinically relevant mycobacteria in microscopy positive clinical specimens and mycobacterial isolates by line probe assay

The Inno LiPA Mycobacteria assay, based on PCR amplification of the 16-23S rRNA spacer region of Mycobacterium species, has been designed for identification of mycobacteria grown in culture media and discrimination between Mycobacterium tuberculosis complex, M. avium, M. intracellulare, M. kansasii, M. gordonae, M. xenopi, scrofulaceum and M. chelonae group including M. abscessus. In order to evaluate the system as a fast diagnostic tool, the assay was for the first time used directly on 14 microscopy positive clinical specimens and 71 isolates and the results were compared to those of conventional identification using 16S rDNA analysis and biochemical properties. The assay only misidentified one strain, which was found to be M. avium complex instead of M. intracellulare as found by the conventional tests. The assay allows rapid discrimination of the eight most clinically relevant mycobacteria in microscopy positive clinical specimens and isolates within 6 h in the same procedural run.