Diagnosis of Pulmonary Tuberculosis in Resource Limited Setting of Rawalpindi

Abstract

Introduction:Tuberculosis is an infectious disease with a high prevalence of about 9 million cases occurring annually. Ziehl Neelsen microscopy is the most widely used technique to detect Acid Fast Bacilli, but it is less sensitive. However, fluorescent microscopy is more helpful with simple diagnostic criteria. Gene Xpert®MTB/RIF assay is a rapid molecular assay that enables diagnosis of Tuberculosis with simultaneous detection of rifampicin resistance. Owing to this fact, we aimed at evaluating the diagnostic accuracy of Ziehl Neelsen microscopy, fluorescent microscopy and Xpert MTB/RIF keeping MTB culture (Mycobacterial Growth Indicator Tube) as a gold standard for the diagnosis of tuberculosis.Methodology:This study was carried out at a tertiary care hospital of Rawalpindi in the year 2016. Patients aged 18 to 70 years irrespective of gender with suspected TB based on history, clinical and radiological examination were included in the study. Respiratory clinical specimens including sputum, Broncho-Alveolar Lavage (BAL), and endobronchial washings were collected. Specimens were processed by MGIT (MTB culture), ZN microscopy, fluorescent microscopy and Gene Xpert MTB/RIF assay.Results:A total of 352 respiratory specimens were tested among which 160 (45%) samples were positive by culture. Out of culture positive samples, 158 samples (98.7%) were GeneXpert TB positive while 2 were negative. While only 49 (30.6%) were positive on ZN microscopy and 89 (55%) were positive on fluorescent microscopy. Out of the culture negative samples, 2 were positive with ZN microscopy, one was positive with fluorescent microscopy and 3 were positive on Gene Xpert. Sensitivity, specificity, Positive Predictive Value (PPV), Negative Predictive Value (NPV) and diagnostic accuracy of ZN Smear microscopy was 39%, 99.5%, 96%, 63% and 14.5% respectively. Sensitivity, specificity, PPV, NPV and diagnostic accuracy of fluorescent smear microscopy was 55% and 99.5%, 98%, 72% and 79% respectively. Sensitivity, specificity, PPV, NPV and diagnostic accuracy of Gene XPERT was 98% and 99%, 98%, 99% and 98% respectively.Conclusion:In countries like Pakistan where Tuberculosis is endemic, the diagnostic accuracy with highest sensitivity and specificity was Gene Xpert Polymerase Chain Reaction (PCR) MTB/RIF assay which can help in well-timed diagnosis of the disease.

Effect of Isoniazid Preventive Therapy on Tuberculosis Prevalence among HIV Patients Attending Bahati Comprehensive Care Centre, Nairobi, Kenya

“…On the other hand the study findings were comparable with those recorded in Ethiopia (14.2%) [19]. These finding would be attributed to the fact that in this age category (20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39), people are normally in institutions of learning, which are often crowded increasing transmission of this air borne disease. Also because of peer pressure which is common during this period, engaging in irresponsible behavior like drug abuse coupled with the already depressed immunity due to HIV makes the body vulnerable to TB disease [10].…”

“…The current study findings were relatively higher than those observed in previous studies in South Africa (15.9%) [18], Zimbabwe (3.0%) [8], Indonesia (Hasan Sadikin hospital) (4.3%) [9] Ethiopia 16.32% [4], (27.8%) [19] (13.4%) [5], (8.8%) [1]. On the other hand the findings were comparable with results from a previous study conducted in Egypt (Al-Hussein university) (36.7 %) [20], but the findings were relatively low than previous study findings in Pakistan 49.46% [21], (98.7) [22].…”