Line probe assay in the rapid detection of rifampin-resistant Mycobacterium tuberculosis directly from clinical specimens.

The sensitivity of a PCR-based line probe assay (Inno-LiPA Rif. TB Assay; Innogenetics NV Zwijndrecht, Belgium) was studied by using nested-PCR technique. A total of 75 specimens, representing various body locations from 70 suspected tuberculosis patients were obtained. LiPA yielded 30 Mycobacterium tuberculosis complex positive results (sensitivity 58.8%, compared with final diagnoses) whereas culture for M. tuberculosis was positive in 18 specimens (sensitivity 35.3%). Genotypic rifampin resistance testing by LiPA showed that 7 specimens contained rpoB mutations associated with RMP resistance, and sequencing data of the rpoB gene and LiPA patterns agreed in 29 of 30 M. tuberculosis positive specimens (96.7%). This indicates reliable performance, which makes the test suitable for the rapid determination of resistance to rifampin directly in clinical samples. However, the best results are obtained if LiPA is combined with conventional staining and culture methods.