Molecular identification and characterization of rifampicin-resistant Mycobacterium tuberculosis isolates by line probe assay: an approach for rapid diagnosis of multidrug-resistant tuberculosis.

AIM

Early identification and characterization of rifampicin-resistant (R(r)) Mycobacterium tuberculosis isolates recovered from the samples of tuberculosis (TB) patients in the Aegean (West Anatolian) Region was intended.

METHODS AND RESULTS

Sixty isolates [47 (78.3%) multidrug-resistant (MDR)], which were identified as M. tuberculosis complex and phenotypically resistant to rifampicin by both BACTEC mycobacteria growth indicator tube (MGIT) 960 and 460 systems were analysed by a commercial line probe assay (INNO-LiPA Rif TB). The concordance of LiPA with the in vitro susceptibility test was found as 98.3%. Among the isolates, S531L (R5 pattern; 46.7%) and L511P/R, S512T, Q513L/K (DeltaS1 pattern; 11.7%) were the most frequent mutation patterns. As compared with the BACTEC systems and conventional techniques for cultivation, identification and in vitro susceptibility testing, INNO-LiPA Rif TB after cultivation in BACTEC MGIT 960 system provided an average of 20 days early diagnosis of R(r)M. tuberculosis isolates.

CONCLUSIONS

Rapid molecular identification and characterization of R(r)M. tuberculosis isolates after BACTEC MGIT 960 cultivation would be useful for faster diagnosis, infection control and planning of accurate treatment in MDR-TB patients.

SIGNIFICANCE AND IMPACT OF THE STUDY

Patients with MDR-TB need a specified treatment and efficient follow-up strategies. Rapid and practical methodologies to diagnose and follow these patients should be applied in routine use.