Abstract

MICROSCOPIC OBSERVATION OF DRUG SUSCEPTIBILITY TESTING-RAPID, RELIABLE AND COST EFFECTIVE METHOD TO DETECT DRUG RESISTANCE TB

A. R. Patil* and P. B. Desai

Abstract

Introduction: About one third population of the world are infected with Tuberculosis and now, it become a serious global concern of public health. Multi drug resistance tuberculosis(MDR-TB) is also global health problem. Conventional method and automated methods for the detection drug resistance tuberculosis are either slow or costly. Microscopic observation of drug susceptibility testing (MODS) is use to detect drug resistance TB directly from the sputum and this method is based on the characteristic growth of Mycobacterium tuberculosis (MTB) in liquid media. Aim: Comparison of MODS assay with Conventional culturing method with respect to: detection of Mycobacterial growth and time taken for the culture positive. Comparison Drug resistance between MODS and Conventional method. Method: Total 207 samples were enrolled in this study which were acid fast smear positive sputum among 496 suspected patient. Decontamination procedure were done on all smear positive samples and it used in culturing and Drug susceptibility test (DST) for MODS assay and for conventional DST method. In MODS assay Middle brook 7H9 broth was used as media, with and without critical concentration of Isoniazid (INH) and Refampicin (RIF). Result: Median time taken by the MODS test was 10- 14 day for culture and DST where as 22 days for culture and 66 days for DST took by Conventional method. Sensitivity and specificity was 100% and 97.4% respectively. It was less expensive than Conventional DST method. positive prediction value and negative prediction value was 100%. Conclusion: MODS assay offers a rapid, simple, economical and feasible method for simultaneous culture and DST of MTB.

Keywords: Mycobacterium tuberculosis, Multidrug resistance tuberculosis, Drug susceptibility test. Microscopic drug susceptibility test.