Resazurin assay for rapid drug susceptibility testing of Mycobacterium tuberculosis

Abstract

Introduction: Tuberculosis, a disease of antiquity continues to cause high morbidity and mortality. In Sustainable Development Goals and End Tb Strategy proposed by WHO includes Drug Susceptibility Testing as major component. Conventional methods are time consuming and molecular methods are rapid but expensive and demanding. Resazurin assay is a rapid colorimetric redox indicator method of Drug Susceptibility Testing. Materials and Methods: 67 strains of M. tuberculosis isolated from pulmonary tuberculosis patients were tested using indirect absolute concentration method by resazurin assay and compared with drug incorporated Lowenstein-Jensen media for Isoniazid and Rifamycin. Results: There was 91.5 % and 91.7% concordance between both methods for INH and Rifamycin respectively. Resazurin assay for INH was 100% sensitive and 61.54% specific. Sensitivity and specificity for RMP was 98.04% and 62.5% respectively. The duration required for INH was 7.0 ± 2.07 and for RMP 6.58 ± 1.58 days. Conclusions: Resazurin assay is sensitive, rapid, cheap, technically simple drug susceptibility method.

A capillary-based centrifugal indicator equipped with in situ pathogenic bacteria culture for fast antimicrobial susceptibility testing

“…13 Fluorescence-based AST relies on fluorescent staining of live/dead cells or bacterial metabolic fluorescent indicators when the bacteria are incubated with the antibiotic. 14–16 These approaches significantly reduce the time of AST from 18 ± 2 h to a few hours.…”