Genexpert(MTB)Rif in culture confirmed cases of pulmonary tuberculosis sensitivity of sputum

Abstract

Background: Tuberculosis (TB) is a major public health problem worldwide with the highest mortality occurring in low-income countries.  Accurate and early diagnosis is key to effective treatment, stopping the transmission and ultimately reducing the mortality associated  with the disease.

Aim: To determine the sensitivity of sputum genexpert(mtb)rif for diagnosis of pulmonary tuberculosis (PTB) in culture  confirmed cases.

Methods: This was a cross-sectional study where samples from 80 presumptive cases of PTB were analyzed with  geneXpert at National Hospital Abuja (NHA) and University of Abuja Teaching Hospital (UATH) while the solid culture using Lowenstein  Jensen media was conducted in Bingham University Research laboratory, Nasarawa state.

Results: A total of 80 sputum samples were  evaluated in the final analysis. The mean age of the study participants was 40.18± 14.12 years. Out of the 80 samples analyzed, 24 (30%)  were positive with GeneXpert, while 25 (31.3%) were positive with Mycobactrium tuberculosis (MTB) culture. For geneXpert: accuracy  (98.8%), sensitivity (96.0%), specificity (100%), positive predictive value (PPV) (100%) and negative predictive value((NPV)98.2%). 24 out of  80 sputum samples that tested positive with GeneXpert (MTB)Rif, 4 were rifampicin resistant (RR) representing 16% of MTB isolates  positive with GeneXpert (MTB)Rif.

Conclusion: GeneXpert (MTB)Rif is highly specific for the diagnosis of PTB in sputum samples. The  prevalence of RR with GeneXpert (MTB)Rif in our study was higher compared to previous studies. This further increased the diagnostic performance of geneXpert(MTB)Rif and makes it a useful tool for early, accurate diagnosis of PTB and for simultaneous detection of RR  which is usually considered a marker for DRTB.