Resumen

VASQUEZ MICHEL, Aneth María; CAMACHO, Mirtha  y  MOLINA ORIHUELA, Julia. Molecular and bacteriological analysis of rifampin-resistant Mycobacteryum tuberculosis isolated from seven  regions of Bolivia. BIOFARBO [online]. 2011, vol.19, n.2, pp. 21-27. ISSN 1813-5363.

Tuberculosis remains an important disease worldwide, this disease once considered eradicated in industrialized countries today is reborn with more force caused by drug-resistant strains. This work represents a study of 66 resistant and 71 sensitive strains of Mycobacterium tuberculosis in 7 regions of Bolivia. The objectives were (i) to assess the phenotypic profiles of resistance of these isolates, (ii) to evaluate a method of genotyping (iii) to associate the most frequent mutations in rpoβ gene with the geographical distribution and the clinical condition of patients. The phenotypic susceptibility testing was performed by the proportions method. The genotyping assay was done by probe hybridization. The susceptibility profiles revealed 10% of RIF mono-resistant strains, the rest of these strains were also resistant to isoniazid, 15 % of the last ones were also resistant to estreptomicyn, 2% to ethambutol and 8% were resistant to the 4 first line drugs. Besides, we found 1.5% poliresistant strains. The diagnostic test analysis to assess the effectiveness of the assay reported a sensitivity of 79% and a specificity of 94%. The concordant value between both methods was 0.75. 25% of the strains, expressed indeterminate mutations, among the 75% remaining, the most frequent mutations in relation to geographical distribution were S531L (MUT3) 59% and less frequent H526D (MUT2B) 4%. With regard to the clinical conditions the most frequent were treatment failure 50%, 25% of these  presented new mutations, relapse in 25%, 86% showed known mutations and 14% new mutations. This assay has demonstrated enough reliability in terms of diagnosis and determination of susceptibility, this would allow us to find specific mutations, data that might collaborate to develop new drugs and vaccines to  new Mycobacterium tuberculosis genotypes.

Palabras llave : Rifampicin; genotype; phenotype; mutation; susceptibility; hybridization; resistance; sensitivity; specificity.