Identificação de mutações em genes envolvidos na resistência medicamentosa de Mycobacterium Leprae

Abstract

Leprosy is a chronic infectious disease caused by Mycobacterium leprae. Worldwide efforts to control leprosy with multidrug therapy (MDT), which is a combination of the drugs rifampin, dapsone and clofazimine, have led to a significant reduction in the detection of new cases in recent years. The current control measure for treating leprosy based mainly in MDT is designed to prevent the emergence, transmission and spread of resistant strains of M. leprae. Although resistance has been reported since 1964 to dapsone, since 1976 to rifampin and since 1994 to ofloxacin, determining the prevalence of drug resistance was made possible only with the advent of molecular biology techniques. It is known that mutations in the folp1 gene result in dapsone resistance. Mutations in the rpoB gene are responsible for rifampin resistance. Mutations in the gyrA gene are associated with fluoroquinolone resistance. The aim of this study was to identify mutations in the folp1, gyrA and rpoB genes of M. leprae from leprosy patients being treated at a reference center of dermatologic diseases in the state of Amazonas, Brazil. We utilized molecular biology techniques including conventional Polymerase Chain Reaction (PCR), Leprosy Drug Susceptibility-DNA microarray (LDS-DA) and DNA sequencing. Using the LDS-DA test two mutations in the rpoB gene were observed in two different samples. These mutations were confirmed by DNA sequencing. Through DNA sequencing four mutations in the folp1 gene five mutations in the gyrA gene and six mutations in the rpoB gene were detected. This included two samples that had mutations in both the gyrA and rpoB genes, indicating multidrug resistance (MDR). Primary and secondary drug resistance was confirmed using LDS-DA analysis and DNA sequencing in slit skin smear specimens obtained from leprosy patients, showing the spread of resistant strains of M. leprae in this area of Brazil and the importance to vary the treatment in these leprosy patients to prevent the dissemination of resistant leprosy bacilli.