Prevalence of rifampicin resistance by CB-NAAT in previously treated pulmonary tuberculosis cases

Abstract

INTRODUCTION: CB-NAAT is an automated, semi-quantitative real time PCR assay designed for the rapid and simultaneous detection of mycobacterium tuberculosis and Rifampicin resistance within 2 hours. 'Rifampicin' resistance is a surrogate marker of MDR-TB.

AIMS & OBJECTIVE: To find out Rifampicin resistance in previously treated pulmonary TB patients by CB-NAAT.

METHOD: this was a prospective study conducted over 1 year in 100 previously treated pulmonary TB cases.Two sputum samples of all study subjects were sent for microscopy and CB-NAAT. All data was analysed by Social Sciences v 16.

RESULT: Out of 67 sputum positive cases, 66 (98.50%) were confirmed by CB-NAAT and in 1(1.50%) patients MTB was not detected. Among the MTB detected cases,79.10% were 'R' sensitive and 'R' resistance was 19.40%. among R resistant cases, 46.15%,23.07%,30.77% were failure cases, treatment after default cases and relapse cases respectively. Among 33 sputum negative cases, 48.48% showed MTB positive,out of which 42.42% was R sensitive and 6.06% was R resistant. Overall prevalence of 'R' resistance in previously treated pulmonary TB patients was 15% (15/100).

CONCLUSION: In this study we found 'R' resistance not only in sputum positive previously treated cases but also sputum negative cases which may be a hidden source of MDR-TB. So this test should be encouraged in sputum negative previously treated TB patients.

REFERANCES1. Tuberculosis. WHO Global Tuberculosis Report 2014. http://www.who.int/tb/publications/factsheet_global.pdf.2. Boehme CC, Nabeta P et al. Rapid molecular detection of tuberculosis and rifampicin resistance. N Eng J Med 2010; 363: 1005-1015.