Original Research Article DOI: 10.18231/2348-7682.2017.0006 Panacea Journal of Medical Sciences, January-April,2017;7(1): 19-21 19 A comparative study of sensitivity of sputum microscopy by direct method versus sodium hypochlorite concentration method at RNTCP Centre Kalpana Date 1,* , Neena Nagdeo 2 , Meenal Kulkarni 3 1,2, Associate Professor, Dept of Microbiology, 3 Associate Professor, Dept of Community Medicine, NKP Salve Institute of Medical Sciences & Research Institute & Lata Mangeshkar Hospital, Nagpur, Maharashtra *Corresponding Author: Email: datekalpana@gmail.com Abstract In revised national tuberculosis control program (RNTCP), microscopic examination of sputum for AFB plays an important role in the initial diagnosis of tuberculosis. Decontamination and liquefaction with by 5% sodium hypochlorite increases sensitivity and safety for handling specimen. In this prospective hospital based cross sectional analytical study, patients of all ages and either sex coming to RNTCP centre were included according to RNTCP criteria. From each patient, two samples of sputum were collected one spot and one morning. One set of smears was prepared by RNTCP guidelines and remaining samples were concentrated by using 5% NaOCl, followed by centrifugation and staining with ZN stain. Both set of smears were observed by two observers to remove observer’s bias. A total of 882 patients were included in the study with 577 (65%) males and 305 (35%) females. A total of 172(19.5%) patients were positive by RNTCP method whereas 201(22.79%) patients were positive by concentration method diagnosing 29 additional patients. This constitutes a rise of 3.29%. This constitute 16.86% rise in case detection over RNTCP method. There is a rise in smear positive cases after concentration with 5% sodium hypochlorite solution. The bleach method has advantage over routine RNTCP method as it is simple, does not require any additional expertise, is safe, reagents are also affordable and easily available and could diagnose additional cases. Keywords: Tuberculosis, Sodium hypochlorite, Sputum microscopy. Introduction Tuberculosis (TB) remains a worldwide public health problem despite the fact that the causative organism was discovered more than 100 years ago. (1) The major objective of the TB control programs is to identify and treat the patients with infectious pulmonary tuberculosis, the diagnosis of which relies on a bacteriological examination of the sputum. Direct microscopy with Ziehl Neelsen staining is still most widely used and it is specific, fast and cheap method. The program has approved LED microscopes but these are not provided at every centre. The culture of Mycobacterium is the reference method for the detection of the tubercle bacilli, but it is prohibitively slow and it requires special safety procedures in laboratories. (2) Many automated culture systems and molecular techniques have been developed which require less turnaround time but are costly. In revised national tuberculosis control program (RNTCP), microscopic examination of sputum for AFB plays an important role in the initial diagnosis of tuberculosis. The microscopic examination requires 10 (4) bacilli per milliliter of sputum in order to be detected on smear. Considering the amount of sputum material that is examined in oil immersion field, chances of missing the organism are high thus reducing the sensitivity. Much of the transmission of TB can occur even before the concentration in sputum reaches a critical level when it is diagnosed. A negative smear does not exclude the diagnosis of tuberculosis, as about 55% of pulmonary tuberculosis cases worldwide harbors low bacillary load. It has also been established that sputum smear microscopy is less sensitive in HIV – TB co infection where sputum smear tends to be negative. (3,4,5) The concentrations of 2-5% of Sodium hypochlorite (NaOCl) digest the sputum products and they inactivate the mycobacteria without altering their structures, so that even when they are killed, they can still be stained and observed. This provides a greater security for laboratory use. Further centrifugation or sedimentation concentrates the acid fast bacilli (AFB) in the mixture and it increases the rate of the positivity. (6) With this background an operational research was planned to look for increase in sensitivity of sputum smear microscopy by concentration after pre-treatment with sodium hypochlorite over routine RNTCP method. Materials and Methods This prospective hospital based cross sectional analytical study was carried out as an operational research in the Department of Microbiology, NKPSIMS & RC, Nagpur after obtaining permission from Institutional Ethics Committee. Patients of all ages and either sex coming to RNTCP centre were included according to RNTCP criteria, having:  Cough for two weeks or more duration  Known contacts of sputum smear positives irrespective of duration of cough  Extra pulmonary TB irrespective of duration of cough. After obtaining informed consent, two sputum samples (1spot and 1 morning sample) from each