Agents of Systemic and Subcutaneous Mucormycosis and Entomophthoromycosis

Abstract

Mucormycosis and entomophthoromycosis are invasive fungal infections caused by environmental nonseptate filamentous fungi. Mucormycosis is caused by the ubiquitous Mucorales fungi and occurs mostly in immunocompromised patients or those with diabetes mellitus. Entomophthoromycosis is caused by the Entomophthorales fungi, found mostly in warm climates. According to the classification proposed by Hibbet et al. the subphylum Entomophthoromycotina contains the order Entomophthorales, which is subdivided into two families: the Ancylistaceae and Basidiobolaceae, containing the genera Conidiobolus and Basidiobolus, respectively. There are 27 species in the genus Conidiobolus, but only two (C. coronatus and C. incongruus) have been recovered from clinical specimens, while in the genus Basidiobolus, B. ranarum is the only species known to cause human disease. Several recent reports have suggested that the incidence of mucormycosis is increasing, based on single-center studies. Mucormycosis represents 2% of invasive fungal infections following solid organ transplantion (SOT), mostly after kidney transplantation. Mucormycosis can also develop in human immunodeficiency virus-infected patients or intravenous drug abusers. Blood cultures have no diagnostic value, as they are almost always negative, despite the fact that mucormycosis is an angioinvasive disease. Demonstration of hyphae in clinical samples is important for the diagnosis of mucormycosis. In summary, new molecular tools have been developed for the diagnosis of mucormycosis and the identification of Mucorales fungi in tissues. Culture results should always be interpreted in light of the clinical presentation and along with the results of direct examination and histopathology.