Prospective multicentre evaluation of the direct nitrate reductase assay for the rapid detection of extensively drug-resistant tuberculosis

Results: Excellent agreement was obtained for all drugs tested at the majority of sites. The accuracy was 93.7%‐ 100%for rifampicin,88.2%‐100%for isoniazid,94.6%‐100%forofloxacinand 100%forkanamycin.Themajority ofNRAresultswereavailableatday21forsites1,2and 5.Site3 had aturnaroundtimeof13.9 days,at site4 itwas 18.4 days and at site 6 it was 16.2 days. The contamination rate ranged between 2.5% and 12%. Conclusions: Rapiddetectionofdrugresistancebythe direct NRAonsputum smear-positivesamples wasaccurate andeasytoimplementinclinicaldiagnosticlaboratories,makingitagoodalternativeforrapidscreeningforMDRand XDR tuberculosis.