PERFORMANCE AND BIOSAFETY IMPLICATIONS OF GENEXPERT MTB/RIF ASSAY.

uberculosis (TB) is transmitted primarily via aerosol of droplet nuclei. Test methods that involve aerosol-generating procedures expose testing personnel to high biohazard risk. The GeneXpert MTB/RIF (Xpert) assay is a point-of-care test that can be performed outside the biosafety cabinet. Sample preparation by Xpert assay entails shaking and pipetting suggesting that Xpert assay might present some bio-hazard risk to testing personnel. The objective of this study is to evaluate the performance of Xpert assay for the diagnosis of TB and drug resistant-TB (DR-TB) while assessing the killing effect of its sample reagent (SR) on tubercle bacilli. A total of 604 samples were used in evaluating the performance of Xpert assay while 212 samples were used in assessing the killing effect of the SR. Specimen for Xpert was processed using the SR as per standard protocol. Two drops of the processed sputum was inoculated unto Lowenstein-Jenseen (LJ) medium. Sputum samples for culture were digested and decontaminated by modified Petroff method. About 2 drops of decontaminated specimen were inoculated unto LJ medium. All inoculated medium were monitored for growth for upward of 8 weeks. Using Xpert assay 440(72.9%) and 164(27.2%) were Mycobacterium tuberculosis (MTB)-negative and MTB-positive respectively. Among the MTB-positive strains, 95(57.9%) were sensitive to rifampicin, 68(41.5%) were rifampicin resistant and 1(0.6%) was rifampicin indeterminate. MTB was detected in 54(32.9%) samples obtained from HIV -positive patients. Of these, 10(18.5%) were rifampicin resistance while 44(81.5%) were rifampicin sensitive. Out of the