| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 2524524 | Biomedicine & Pharmacotherapy | 2011 | 4 Pages |
We determined the susceptibility profile of 80 Mycobacterium tuberculosis (MTB) clinical isolates from Brazil against isoniazid (INH) and rifampicin (RIF) drugs by two phenotypic methods (Resazurin Microtiter Assay - REMA and BACTEC™ MGIT™ Mycobacterial Detection System). DNA polymorphisms were also determined by PCR-SSCP in isolates resistant to INH and RIF. BACTEC™ MGIT™ 960 detected 22 susceptible isolates to INH and RIF, 48 MDR isolates (resistant at least to INH and RIF) and nine mono-resistant isolates (eight to INH and one to RIF). REMA performance was determined by Receiver Operating Characteristic curve, whose assay was validated utilizing as reference the BACTEC™ MGIT™ 960 system. ROC curve showed cut-off values of 0.0625 μg/mL and 0.125 μg/mL, for INH and RIF, respectively. REMA-INH demonstrated sensitivity and specificity of 100% while REMA-RIF showed sensitivity of 97.2% and specificity of 100%. PCR-SSCP detected DNA polymorphisms in 87.5% and 75.5% of isolates classified as INH-resistant and RIF-resistant, respectively. One discordant sample found to RIF (resistant by BACTEC™ MGIT™ 960 and susceptible by REMA) showed no mutation by PCR-SSCP. In conclusion, our studies demonstrated that the combination of phenotypic method REMA, which allowed rapid detection of MDR-MTB with higher levels of sensitivity and specificity, with the genotypic method PCR-SSCP, which demonstrated high accuracy in the search of polymorphisms in the resistance genes, proved to be a useful strategy to study MDR-MTB clinical isolates from national reference center located in São Paulo city.
