The performance of the nitrate reductase assay (NRA) was compared with the proportion method (PM) on
Lowenstein-Jensen medium and the BACTEC MGIT960 assay under routine conditions using 160 clinical isolates
of Mycobacterium tuberculosis with a high proportion of resistant strains. The mean time to obtain results was 8.8
days and the overall agreements between NRA and PM and NRA and M960 were 95% and 94%, respectively. NRA
was easy to perform and represents a useful tool for the rapid screening of drug-resistant
Mycobacterium tuberculosis
strains in
low-resource countries.