Tuberculosis is an infectious disease caused by Mycobacterium tuberculosis, a bacterium that primarily affects the lungs and is believed to have originated over 150 million years ago. The disease is curable and preventable. The treatment against TB comprises six months of rifampin, isoniazid, streptomycin, ethambutol and pyrazinamide; however, this has been complicated by the surface of resistant strains of M. tuberculosis. These strains are classified as multidrug (MDR-TB) and extremely drug resistant (XDR-TB). Associations have been found between mutations in the katG gene and resistance to isoniazid, the rpoB gene and rifampicin resistance, and rpsL gene and streptomycin resistance. The presence and frequency of these mutations may vary according to the geographical area. In this research, antibiograms were performed to 13 Mycobacterium tuberculosis strains collected from 2012 to 2014 in the state of Michoacan. The antibiograms were performed using the equipment BACTEC-MGIT 960. As a result it was found that 23.1% of the mentioned strains were resistant to rifampicin and streptomycin. The mutations were detected by PCR amplification, sequencing the regions of interest in the study genes, and their alignment with the software 6.06 Mega. The results were compared with the TB Database and the TB Drug Resistance Mutation Database. The katG gene presented the highest number of mutations with 46.15%, the rpoB gene exhibited only one mutation (7.69%) and the rpsL gene presented no mutation. The two strains resistant to isoniazid showed the mutation Ser315Thr, already reported in the database and the most commonly reported in the literature. Of the three strains resistant to rifampin, only one showed a mutation, the Ser450Leu mutation in the rpoB gene, which coincides with other studies in the country, but this one is outside the RRDR region where most of the mutations appear according to the literature.
La tuberculosis es una enfermedad infecciosa causada por Mycobacterium tuberculosis, una bacteria que afecta principalmente a los pulmones y se cree que se originó hace más de 150 millones de años. La afección es curable y se puede prevenir. El tratamiento contra la tuberculosis comprende seis meses con rifampicina, isoniazida, estreptomicina, etambutol y pirazinamida; sin embargo, este se ha ido complicando con la aparición de cepas de M. tuberculosis resistentes, estas cepas se han clasificado como Multidrogorresistentes (MDR- TB) y extremadamente drogorresistentes (XDR-TB). Se han encontrado asociaciones entre mutaciones en el gen katG y la resistencia a isoniazida; el gen rpoB y la resistencia a rifampicina y el gen rpsL y la resistencia a estreptomicina. La presencia y frecuencia de estas mutaciones puede variar de acuerdo a la zona geográfica. En este trabajo se realizaron los antibiogramas de 13 cepas de Mycobacterium tuberculosis recolectadas del 2012 al 2014 en el estado de Michoacán. Los antibiogramas fueron realizados mediante el equipo BACTEC-MGIT 960. Como resultado se encontró que el 23.1% de las cepas mencionadas fue resistente a rifampicina y a estreptomicina. Las mutaciones se detectaron mediante amplificación por PCR, secuenciación de las regiones de interés en los genes de estudio, y su alineamiento con el programa Mega 6.06. Los resultados se compararon con TB Database y TB Drug Resistance Mutation Database. El gen katG presentó el mayor número de mutaciones con un 46.15%, el gen rpoB presentó solo una mutación (7.69%) y el gen rpsL no presentó ninguna mutación.
