Drug susceptibility testing of Mycobacterium tuberculosis with nitrate reductase assay.
The nitrate reductase assay (NRA) was evaluated for susceptibility testing of Mycobacterium tuberculosis using 80 clinical isolates of M. tuberculosis and H37Rv as a control strain. All isolates were tested by the proportion method and the NRA for isoniazid (INH), rifampicin (RIF), streptomycin (STR) and ethambutol (ETM). The proportion method was carried out according to NCCLS on Löwenstein-Jensen (LJ) medium and the NRA on LJ medium containing 1000 microg/ml potassium nitrate (KNO(3)). After incubation for 7, 10, 14 and 21 days, Griess reagent was added to each LJ medium and nitrate reduction was determined by a colour change. Comparing the NRA with the proportion method, sensitivities were 100, 100, 82.1 and 92.2% for INH, RIF, STR and ETM, respectively. Specificities were 100, 100, 92.3 and 100% for INH, RIF, STR and ETM, respectively. The results of 2, 22 and 56 isolates were obtained after 7, 10 and 14 days, respectively. The proportion method result were read at 21-28 days. The NRA is rapid, inexpensive and easy to perform. Our results indicated that the NRA is suitable for the early determination of INH and RIF resistance in countries where sophisticated procedures are not always available.
Department of Microbiology and Clinical Microbiology, Medical School, Ondokuz Mayis University, 55139 Samsun, Turkey. noahmet@yahoo.com
Ahmet Yilmaz
AY
Coban
Asuman
A
Birinci
Bora
B
Ekinci
Belma
B
Durupinar
D000995:Antitubercular Agents / Q000494:pharmacology*; D003116:Color; D004977:Ethambutol / Q000494:pharmacology; D005029:Ethylenediamines; D016166:Free Radical Scavengers; D007538:Isoniazid / Q000494:pharmacology; D008826:Microbial Sensitivity Tests / Q000379:methods*; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000378:metabolism; D050901:Nitrate Reductase; D009565:Nitrate Reductases / Q000378:metabolism*; D009566:Nitrates / Q000378:metabolism; D009573:Nitrites / Q000032:analysis / Q000737:chemistry; D010084:Oxidation-Reduction; D017680:Potassium Compounds / Q000378:metabolism; D012293:Rifampin / Q000494:pharmacology; D012680:Sensitivity and Specificity; D013307:Streptomycin / Q000494:pharmacology; D013424:Sulfanilamides; D013997:Time Factors
D000995:Antitubercular Agents; D005029:Ethylenediamines; D016166:Free Radical Scavengers; C095000:Griess reagent; D009566:Nitrates; D009573:Nitrites; D017680:Potassium Compounds; D013424:Sulfanilamides; D004977:Ethambutol; D009565:Nitrate Reductases; D050901:Nitrate Reductase; C023844:potassium nitrate; D007538:Isoniazid; D012293:Rifampin; D013307:Streptomycin