Detección rápida de resistencia a drogas en Mycobacterium tuberculosis mediante PCR-SSCP y PCR- Heteroduplex

Abstract

Objective: Early detection of Mycobacterium tuberculosis susceptibility to two anti tuberculous drugs,rifampin and isoniazid using PCR and conformational electrophoresis. Material and methods: Two amplification assays were implemented for the rpoB and katG genes and susceptibility to antituberculous agents was determined by heteroduplex and SSCP in 31 clinical samples obtained from patients with positive smear pulmonar tuberculosis.The phenotypical characterization of susceptibility to antituberculous agents was performed using proportion method. Results: PCR assays detected up to 2,5 pg of M. tuberculosis genomic DNA, no amplifications of DNA of other mycobacteria and common bacteria of buccal flora was performed. The general concordance between the molecular and conventional detection of rifampin and isoniazid susceptibility was 96,7% and 83,9% (p<005) respectively. However, a 100% and 90,9% concordance (p<0,05) for rifampin and isoniazid respectively was found only in patients who received previous treatment. Moreover, this resistance detection system can give results 48 hours after the clinical sample is obtained. Conclusion: These systems showed to be an excellent diagnosis alternative for the early identification of patients infected with drug-resistant Mycobacterium tuberculosis. It will potentially allow the use of timely and optimal treatment schemes that may contribute to the control and prevention of multidrug-resistant strains that affect public health in our country.