Evaluation of rapid alternative methods for drug susceptibility testing in clinical isolates of Mycobacterium tuberculosis
AUTOR(ES)
Mengatto, Luciano, Chiani, Yosena, Imaz, María Susana
FONTE
Memórias do Instituto Oswaldo Cruz
DATA DE PUBLICAÇÃO
2006-08
RESUMO
A study was carried out to compare the performance of a commercial method (MGIT) and four inexpensive drug susceptibility methods: nitrate reductase assay (NRA), microscopic observation drug susceptibility (MODS) assay, MTT test, and broth microdilution method (BMM). A total of 64 clinical isolates of Mycobacterium tuberculosis were studied. The Lowenstein-Jensen proportion method (PM) was used as gold standard. MGIT, NRA, MODS, and MTT results were available on an average of less than 10 days, whereas BMM results could be reported in about 20 days. Most of the evaluated tests showed excellent performance for isoniazid and rifampicin, with sensitivity and specificity values > 90%. With most of the assays, sensitivity for ethambutol was low (62-87%) whereas for streptomycin, sensitivity values ranged from 84 to 100%; NRA-discrepancies were associated with cultures with a low proportion of EMB-resistant organisms while most discrepancies with quantitative tests (MMT and BMM) were seen with isolates whose minimal inhibitory concentrations fell close the cutoff. MGIT is reliable but still expensive. NRA is the most inexpensive and easiest method to perform without changing the organization of the routine PM laboratory performance. While MODS, MTT, and BMM, have the disadvantage from the point of view of biosafety, they offer the possibility of detecting partial resistant strains. This study shows a very good level of agreement of the four low-cost methods compared to the PM for rapid detection of isoniazid, rifampicin and streptomycin resistance (Kappa values > 0.8); more standardization is needed for ethambutol.
Documentos Relacionados
- Evaluation of rapid radiometric method for drug susceptibility testing of Mycobacterium tuberculosis.
- Evaluation of Etest Strips for Rapid Susceptibility Testing of Mycobacterium tuberculosis
- Photographic and Luminometric Detection of Luciferase Reporter Phages for Drug Susceptibility Testing of Clinical Mycobacterium tuberculosis Isolates
- Evaluation of Etest for Susceptibility Testing of Multidrug-Resistant Isolates of Mycobacterium tuberculosis†
- Evaluation of mycobacteria growth indicator tube for recovery and drug susceptibility testing of Mycobacterium tuberculosis isolates from respiratory specimens.