E.A. El Toum's research while affiliated with University of Khartoum and other places

In this prospective study, three types of tissue reaction to mycetoma grains are described. Type I reaction is characterized by the adherence of neutrophils to the surface of the grain leading to its disintegration. In Type II reaction, the fragmented grain and the dead neutrophils are cleared by macrophages and multinucleated giant cells, while in Type III reaction there is a discrete well developed epithelioid granuloma with Langhans's giant cells. The three types of reaction are usually seen in different combinations in the same lesion.

This is the first report on the fine structure of Actinomadura pelletieri. The in vitro ultrastructure of the organism and that of the grain in vivo were similar. The grain consisted of packed filaments with a faintly electron-dense matrix in between. The individual filament was septate, the cytoplasm was either vacuolated or contained intracellular organelles and the cytoplasmic membrane was adherent to the filamentous wall, which has three electron-dense and two electron-lucent layers. The absence of cement substance around the grain may partially explain the aggressive and destructive behaviour of this organism and may probably also explain its good response to medical treatment. The inflammatory host reaction was similar to that seen with all mycetoma organisms except that there was a massive neutrophil reaction. This was confirmed by electron microscopy.