title: Field evaluation of the direct detection of multidrug resistant Mycobacterium tuberculosis by nitrate reductase assay on 7H11 agar.
abstract: In this study we evaluated the performance of colorimetric nitrate reductase assay (NRA) on Middlebrook 7H11 agar instead of Lowenstein-Jensen medium for detection of isoniazid (INH) and rifampin (RIF) resistance directly on 114 smear positive sputum specimens and compared the results with direct proportion method on LJ medium. The results of both methods were in 100% agreement for detection of RIF resistance while agreement for INH was 96.4%. The average turnaround time for NRA was 18.6 days and majority of the specimens gave positive results within 21 days. Thus direct NRA testing on smear positive sputum specimens by using 7H11 agar could be used as a fast, reliable and inexpensive method in resource starved settings.
authors.affiliation: Department of Pathology, Combined Military Hospital, Dera Ismail Khan, Pakistan. luqmansatti@hotmail.com
authors.forename: Luqman
authors.initials: L
authors.lastname: Satti
authors.forename: Aamer
authors.initials: A
authors.lastname: Ikram
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Palomino
authors.forename: Anandi
authors.initials: A
authors.lastname: Martin
authors.forename: Farooq Ahmad
authors.initials: FA
authors.lastname: Khan
mesh_terms: D000362:Agar; D000995:Antitubercular Agents / Q000494:pharmacology*; D003124:Colorimetry / Q000379:methods; D003430:Cross-Sectional Studies; D003470:Culture Media; D024901:Drug Resistance, Multiple, Bacterial; D006801:Humans; D007538:Isoniazid / Q000494:pharmacology; D008826:Microbial Sensitivity Tests / Q000379:methods; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000201:enzymology / Q000254:growth & development; D050901:Nitrate Reductase / Q000378:metabolism*; D015203:Reproducibility of Results; D012293:Rifampin / Q000494:pharmacology; D013183:Sputum / Q000382:microbiology; D018088:Tuberculosis, Multidrug-Resistant / Q000175:diagnosis*
chemical_list: D000995:Antitubercular Agents; D003470:Culture Media; D000362:Agar; D050901:Nitrate Reductase; D007538:Isoniazid; D012293:Rifampin