INTRODUCTION
Tuberculosis (TB) is a chronic contagious disease instigated by Mycobacterium tuberculosis (MTB). TB spreads through aerosols of TB germs into the air and typically affects the lungs and other organs of the human body [1].
Tuberculosis is a major worldwide public health issue and is graded in top ten causes of mortalities worldwide. In 2016, World Health Organization (WHO) reported 10.4 million new cases of TB and 1.7 million mortalities related to TB. More than 95% of mortalities reported were from low-income and middle-income countries. Moreover, 56% of these cases were reported in five Asian countries (China, India, Indonesia, Pakistan and Philippines). Pakistan is included in list of seven most endemic countries where each year an estimated 510 000 new TB cases are identified [1, 2].
Conventional methods of diagnosis including sputum microscopy and mycobacterial tuberculosis culturing are mostly in use particularly in developing countries. Also, multidrug resistant tuberculosis (MDR-TB), where bacterial strain become resistant to first-line anti TB drugs (Isoniazid, Pyrazinamide, Rifampicin), has emerged as threats to TB treatment [3, 4]. In 2016, globally 600 000 new cases of rifampicin were notified in which 0.46 million cases had MDR. Moreover, approximately 15 000 emerging new drug resistant TB cases occur each year [1, 2]. For all new TB cases, WHO recommends standardized short course chemotherapy based on a regimen of four first-line drugs taken for 6-8 months [5].
GeneXpert MTB/RIF (Cepheid Sunnyvale, United States) is a novel revolutionary development in tuberculosis diagnostics with endorsement from WHO [6-8]. The accuracy of GeneXpert has been reported as high in many previous studies [9, 10]. GeneXpert may be used for diagnosis of MTB and particularly rifampicin (RIF) resistant TB cases. Early detection of MTB and MDR is important in diagnosis to improve the successful treatment rate and decrease TB transmission [11, 12].
Diagnosis with GeneXpert is also becoming common in developing world including Pakistan. The main objective of this study was to compare the performance of GeneXpert with common conventional methods of Mycobacteria Growth Indicator Tube (MGIT) and Ziehl-Neelsen (ZN) staining for smear microscopy.