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.