Resistance of Leishmania (Leishmania) amazonensis and Leishmania (Viannia) braziliensis to nitric oxide correlates with disease severity in Tegumentary Leishmaniasis.

Background: Nitric oxide (NO*) plays a pivotal role as a leishmanicidal agent in mouse macrophages. NO* resistant Escherichia coli and Mycobacterium tuberculosis have been associated with a severe outcome of these diseases.

Methods: In this study we evaluated the in vitro toxicity of nitric oxide for the promastigote stages of Leishmania (Viannia) braziliensis and Leishmania (Leishmania) amazonensis parasites, and the infectivity of the amastigote stage for human macrophages.