European Journal of Biomedical and Pharmaceutical Sciences

DIAGNOSTIC YIELD OF BRONCHOALVEOLAR LAVAGE CARTRIDGE BASED NUCLEIC ACID AMPLIFICATION TEST (CB NAAT) IN SMEAR NEGATIVE PULMONARY TUBERCULOSIS.

Dr. Pankaj Wagh* and Dr. Jigneshkumar Patel

ABSTRACT

Introduction: Tuberculosis (TB) is one of the most common communicable diseases affecting all age groups in low-income countries. According to the WHO Global Report 2015, there were an estimated 10.4 million new (incident) TB cases worldwide, of which 5.9 million (56%) were among men, 3.5 million (34%) among women and 1.0 million (10%) among children. Bronchoscopy with Bronchoalveolar Lavage (BAL) is very useful in patients suspected of pulmonary tuberculosis. Recently, a cartridge system with multicolour real-time PCR capacity for the detection of Mycobacterium tuberculosis (MTB), commonly known as Gene-Xpert, has been developed which detects mutations in the 81-bp Rifampicin Resistance-Determining Region (RRDR) of the rpoB gene within 2 hours, that occurs in 95 - 98% of all rifampin-resistant strains. Aims and Objectives: To measure the diagnostic yield of BAL fluid CB NAAT to detect Mycobacterium Tuberculosis and to rule out rifampicin resistance on the same day. Method and materials: We performed an analytical study to evaluate pulmonary tuberculosis in the Department of Pulmonary Medicine of our hospital.All the patient included in this study underwent Bronchoscopic evaluation and BAL was taken. A patient was considered a tuberculosis-suspect, on the basis of clinical and radiological features compatible with a diagnosis of pulmonary tuberculosis.A smear-negative case was one in whom two samples, one spot sample and one early morning sample did not reveal acid fast bacilli when examined by microscopy with Ziehl Nelson stain and fluorescent microscopy. Results: We evaluate 40 patient with mean age was 38.56 ± 19.045 years. About 25 patients (62.5%) were males while the rest were female patients i.e 15 (37.5%). BAL CB NAAT was positive in 27 (67.5%) and negative in 13(32.5%) patients.BAL positivity by direct smear was present in 13(32.5%) patient and BAL positivity by culture was present in 35 (87.5%). Conclusion: Bronchoalveolar lavage gene Xpert(CB NAAT) had a superior diagnostic yield to detect Mycobacterium tuberculosis and rifampicin resistance (with high sensitivity and specificity).This test has the advantages of being inexpensive, requires less manpower and gives results on the same day. Our study highlights that XpertMTB/RIF has high sensitivity and specificity for diagnosis of both smear positive and smear negative PTB cases with high rates of detection of RIF resistance.

Keywords: MTB, Bronchoalveolar Lavage, Gene Xpert, Rifampicin.