Molecular detection of resistance to rifampicin and isoniazid in tuberculosis patients in Senegal

The aim of this study was to use molecular methods to determine the profile of resistance to rifampicin (RMP or RIF) and isoniazid (INH) in mycobacteria from tuberculosis patients in Senegal. Sputum samples (48) received by the mycobacterial laboratory of the National Antituberculosis Program (NATP) in Senegal between 2012 and 2014 were studied. Most of these samples came from patients in treatment failure or relapse (58.33%). They were tested with the Xpert MTB/RIF or line-probe assays (LPAs) or both. 17 (35.41%) isolates resistant to INH, 16 (33.33%) resistant to RMP, and 16 that were multidrug-resistant (MDR) (33.33%) were identified. Two isolates (4.16%) were susceptible to INH, but resistant to RMP (INH-S/RIF-R). The molecular tests facilitated the rapid detection of MDR isolates. However, INH resistance should be assessed in all cases in which RIF resistance is detected, given the demonstrated existence of INH-S/RIF-R strains.