Analysis, comparison, and significance of nested polymerase chain reaction with conventional methods for the diagnosis of pulmonary and extrapulmonary tuberculosis among the rural population of North India

Abstract

Introduction: Tuberculosis (TB) is one of the most common infectious diseases among the Indian population, especially in rural scenario. It affects young people in majority. Living at slum areas and poverty are predisposing etiological factors. The diagnosis of TB is based on microbiology, cytology, and histopathology. Materials and Methods: The present study was carried out in the Department of Microbiology in collaboration with the Department of Pathology, UPUMS, Saifai, Etawah, UP, India, from January 2015 to June 2016. Samples were collected from suspected tubercular patients. A total of 101 samples were collected including tissue, ascitic fluid, pleural fluid, cerebral fluids, bronchoalveolar lavage, tracheal aspirates, urine, sputum, and pus from clinically suspected cases. Ziehl–Neelsen (ZN) staining, fluorescent staining with auramine phenol, culture on Löwenstein–Jensen (LJ) media, mycobacterial growth indicator tube (MGIT), and Middlebrook media were done. Subsequently, biochemical tests such as niacin detection, catalase test, and nitrate reduction test were done for identification of mycobacteria. Nested polymerase chain reaction (PCR) was performed for the detection of Mycobacteria in clinical samples. Results: Of the 101 suspected tubercular patients, males were more, and the maximum age group involved was 21–40 years. ZN staining was found positive in 16 cases which included ten extrapulmonary and six pulmonary, whereas auramine phenol was found positive in 22 cases which included 14 extrapulmonary and 8 pulmonary. Of 101 patients, 35 (34.6%) were found to be LJ culture positive, whereas 49 (48.5%) were found positive with MGIT culture. PCR for TB was found maximum, which was 76 (75.2%). Conclusion: TB is common among the young group with more predilection among males. Smear- and culture-negative specimens could not rule out TB. Nested PCR proved to be highly sensitive in detecting Mycobacterium tuberculosis DNA. Hence, when TB is suspected, a combination of conventional test and newer rapid techniques such as PCR is always required for the early diagnosis and treatment of TB.

Keywords

• Histopathology
• microbiology
• nested polymerase chain reaction
• tuberculosis