Rapid detection of resistant tuberculosis by nitrate reductase assay performed in three settings in Brazil

• Published in: Journal of antimicrobial chemotherapy 2009-10, Vol.64 (4), p.794-796
• Main Authors: Shikama, Maria de Lourdes, Silva, Regina Ruivo Ferro E., Martins, Maria Conceição, Giampaglia, Carmen Maria Saraiva, Oliveira, Rosângela Siqueira, Silva, Rosmari F. A. M., Silva, Paula Ferro E., da Silva Telles, Maria Alice, Martin, Anandi, Palomino, Juan Carlos
• Format: Article
• Language: English
• Subjects: Antibiotics; Antibiotics. Antiinfectious agents. Antiparasitic agents; Antitubercular Agents - pharmacology; Bacterial diseases; Biological and medical sciences; Brazil; Comparative studies; Drug resistance; drug susceptibility testing; Human bacterial diseases; Humans; Infectious diseases; M. tuberculosis diagnostic; Medical sciences; MGIT 960; Microbial Sensitivity Tests - methods; Mycobacterium tuberculosis - drug effects; Mycobacterium tuberculosis - enzymology; Nitrate Reductase - metabolism; NRA; Pharmacology. Drug treatments; proportion method; Public health; Reproducibility of Results; Time Factors; Tuberculosis; Tuberculosis and atypical mycobacterial infections; Tuberculosis, Multidrug-Resistant - diagnosis; Tuberculosis, Multidrug-Resistant - microbiology
• ISSN: 0305-7453; 1460-2091
• DOI: 10.1093/jac/dkp284

Objectives To evaluate nitrate reductase assay (NRA) efficacy for streptomycin, isoniazid, rifampicin and ethambutol susceptibility testing of Mycobacterium tuberculosis strains. Methods Results were generated by three laboratories: the Instituto Adolfo Lutz (IAL) Mycobacteria Reference Laboratory and two IAL Regional Laboratories in Santo André and Sorocaba, São Paulo State, Brazil. One hundred and twenty M. tuberculosis strains were simultaneously tested using NRA and the proportion method (PM), while 117 strains were tested using both NRA and BACTEC MGIT 960 (M960). Results Repeatability analysis of NRA results showed rates of 100% for isoniazid and ethambutol and 97% for streptomycin and rifampicin susceptibility detection, representing substantial agreement. McNemar testing of the data also indicates that NRA and PM, as well as NRA and M960, do not differ significantly. On average, NRA results were available after 10 days. Conclusions The data demonstrate that NRA is reliable for susceptibility testing of isoniazid and rifampicin, the two most important drugs for the treatment of tuberculosis. In addition, the reduction in the time necessary to obtain susceptibility results is of fundamental importance.