RESUMO
Background: Mycobacterium leprae was considered the only causal agent of leprosy until Mycobacterium lepromatosis was identified' which it has been suggested has greater pathogenicity and is linked to diffuse lepromatous leprosy (DLL) and Lucio's phenomenon (LPh). Our objective is to identify Mycobacterium spp. in an endemic area of leprosy in Colombia. Methods: The study included cases with a diagnosis of leprosy by clinical and histopathological analysis. DNA extraction and two specific rounds of semi-nested polymerase chain reaction (PCR) were performed in paraffin biopsies skin to identify M. leprae and M. lepromatosis. Demographic, clinical, and histopathological data were extracted and tabulated for analysis. Results: Forty-one cases of leprosy were analyzed. The most frequent clinical diagnosis was lepromatous leprosy (36.6%); there was one case with DLL and two with LPh. The most common histopathological finding was tuberculoid leprosy (36.59%); three cases had negative histopathology. M. lepromatosis was not detected; all cases corresponded to M. leprae including cases with negative histopathology' DLL, and LPh. Conclusion: In this study, M. leprae was the causative agent of leprosy, encompassing even its most severe phenotypic forms. It is appropriate to consider PCR as an indispensable tool for the diagnosis of leprosy and to continue to carry out the active search for M. lepromatosis.