Abstract

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The development of multidrug resistant tuberculosis (MDR-TB) and extensively drug resistant tuberculosis XDR-TB coupled with Human Immunodeficiency Virus Co-infection with TB has brought a major setback in the tuberculosis control strategies worldwide including Nigeria. The Genotype MTBDR plus VER 2.0 is widely recognized for its excellent performance due to its rapid detection of drug resistant tuberculosis especially from acid fast bacilli (AFB) smear-positive pulmonary TB cases which has brought much hope towards reversing the spread of all forms of tuberculosis. The study aimed at evaluating Genotype MTBDR plus VER 2.0 for detection of Drug Resistant-TB from sputum samples of smear-negative pulmonary TB cases. A total of 175 smear-positive and 278 AFB smear-negative sputum samples were purposely selected from sputum samples that were referred to North West Zonal Tuberculosis Reference laboratory. All the samples were rifampicin resistant cases (confirmed by Genxpert) from their respective health centers across North-Western Zone of Nigeria and were then subjected to Line Probe Assay (LPA) using Genotype MTBDR plusver 2.0. The result shows that 87% of the AFB smear-positive samples were identified as positive for Mycobacterium tuberculosis complex (MTBC) by the LPA and 13.7% were negative. Whereas 79%of the AFB smear-negative samples were also detected as negative for MTBC by the LPA and 21% were positive for MTBC. The study further revealed that 44.7% of the AFB smear-positive and 46.5% of AFB smear-negative samples were found to be rifampicin resistant by LPA. Also 36.4% of AFB smear-positive and 34.5% of the AFB smear-negative sample were found to be MDR-TB by the LPA. Most importantly, 15.1% of the smear-positive samples and 17.2% of AFB smear-negative samples were found to be susceptible to both rifampicin and isoniazid by the LPA. The study demonstrated that the Genotype MTBDR plusVer 2.0 detects 87% of the positive smears and 79% of the negative smears as positive and negative for MTBC respectively. Most importantly, it detects 21% of the AFB smear negative samples as positive for MTBC with some of them identified as rifampicin resistant and MDR-TB respectively. This therefore reveals the excellent performance of Genotype MTBDRplusVer 2.0 in the diagnosis of DR-TB both in smear positive samples and smear-negative samples within a short turnaround time.

Keywords: Acid Fast Bacilli, Line Probe Assay, Multidrug resistant Tuberculosis, Smears.