title: Evaluation of direct detection of Mycobacterium tuberculosis rifampin resistance by a nitrate reductase assay applied to sputum samples in Cotonou, Benin.
abstract: The aim of this study was to evaluate a nitrate reductase assay (NRA) performed on smear-positive sputa for the direct detection of rifampin resistance in Mycobacterium tuberculosis. A total of 213 smear-positive sputa with a positivity score of 1+ or more (>1 acid-fast bacillus per field by fluorescence microscopy) were used in the study. The samples were decontaminated using the modified Petroff method, and portions of the resulting suspension were used to perform the NRA. The NRA results were compared with the reference indirect proportion method for 177 specimens for which comparable results were available. NRA results were obtained at day 10 for 15 specimens (9%), results for 88 specimens (50%) were obtained at day 14, results for 66 specimens (37%) were obtained at day 18, and results for the remaining 8 specimens (4%) were obtained at day 28. Thus, 96% of NRA results were obtained in 18 days. Of the 177 specimens, there was only one discrepancy (susceptible according to the NRA and resistant according to the indirect proportion method). NRA is simple to perform and provides a rapid, accurate, and cost-effective means for the detection of rifampin resistance in M. tuberculosis isolates.
authors.affiliation: Laboratoire de Référence des Mycobactéries, BP 817 Cotonou Bénin.
authors.forename: Dissou
authors.initials: D
authors.lastname: Affolabi
authors.forename: Mathieu
authors.initials: M
authors.lastname: Odoun
authors.forename: Anandi
authors.initials: A
authors.lastname: Martin
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Palomino
authors.forename: Séverin
authors.initials: S
authors.lastname: Anagonou
authors.forename: Françoise
authors.initials: F
authors.lastname: Portaels
mesh_terms: D000995:Antitubercular Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001541:Benin / Q000453:epidemiology; D003124:Colorimetry; D012321:DNA-Directed RNA Polymerases; D024881:Drug Resistance, Bacterial; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D009169:Mycobacterium tuberculosis / Q000187:drug effects*; D050901:Nitrate Reductase / Q000378:metabolism*; D012293:Rifampin / Q000627:therapeutic use*; D012680:Sensitivity and Specificity; D013183:Sputum / Q000382:microbiology*; D014397:Tuberculosis, Pulmonary / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology*
chemical_list: D000995:Antitubercular Agents; D001426:Bacterial Proteins; C505805:rpoB protein, Mycobacterium tuberculosis; D050901:Nitrate Reductase; D012321:DNA-Directed RNA Polymerases; D012293:Rifampin