title: Prospective multicentre evaluation of the direct nitrate reductase assay for the rapid detection of extensively drug-resistant tuberculosis.
abstract: OBJECTIVE
  To perform a multicentre study evaluating the performance of the direct nitrate reductase assay (NRA) for the detection of multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis in sputum samples.
  
  
  METHODS
  The study was conducted in six laboratories performing tuberculosis diagnosis that were located in six different countries. The NRA was performed directly on sputum samples in parallel with the reference method used at each site. Detection of resistance was performed for rifampicin, isoniazid, ofloxacin and kanamycin.
  
  
  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% for ofloxacin and 100% for kanamycin. The majority of NRA results were available at day 21 for sites 1, 2 and 5. Site 3 had a turnaround time of 13.9 days, at site 4 it was 18.4 days and at site 6 it was 16.2 days. The contamination rate ranged between 2.5% and 12%.
  
  
  CONCLUSIONS
  Rapid detection of drug resistance by the direct NRA on sputum smear-positive samples was accurate and easy to implement in clinical diagnostic laboratories, making it a good alternative for rapid screening for MDR and XDR tuberculosis.
authors.affiliation: Laboratory of Microbiology, Department of Biochemistry and Microbiology, Ghent University, Ghent, Belgium.
authors.forename: Anandi
authors.initials: A
authors.lastname: Martin
authors.forename: Belen
authors.initials: B
authors.lastname: Imperiale
authors.forename: Pascaline
authors.initials: P
authors.lastname: Ravolonandriana
authors.forename: Ahmet Yilmaz
authors.initials: AY
authors.lastname: Coban
authors.forename: Alper
authors.initials: A
authors.lastname: Akgunes
authors.forename: Aamer
authors.initials: A
authors.lastname: Ikram
authors.forename: Luqman
authors.initials: L
authors.lastname: Satti
authors.forename: Mathieu
authors.initials: M
authors.lastname: Odoun
authors.forename: Pooja
authors.initials: P
authors.lastname: Pandey
authors.forename: Manvi
authors.initials: M
authors.lastname: Mishra
authors.forename: Dissou
authors.initials: D
authors.lastname: Affolabi
authors.forename: Urvashi
authors.initials: U
authors.lastname: Singh
authors.forename: Voahangy
authors.initials: V
authors.lastname: Rasolofo
authors.forename: Nora
authors.initials: N
authors.lastname: Morcillo
authors.forename: Peter
authors.initials: P
authors.lastname: Vandamme
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Palomino
mesh_terms: D054908:Extensively Drug-Resistant Tuberculosis / Q000175:diagnosis* / Q000201:enzymology*; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000592:standards*; D050901:Nitrate Reductase; D011237:Predictive Value of Tests; D011446:Prospective Studies; D013997:Time Factors
chemical_list: D050901:Nitrate Reductase
keywords: Mycobacterium tuberculosis; multidrug resistance; nitratase