Absidia

Absidia is a genus of filamentous fungi in the family Mucoraceae, order Mucorales. Members are common environmental molds found in soil, decaying vegetation, and stored foods, and they may grow rapidly on nutrient-rich media as cottony, white-to-grey colonies.

Anatomy and reproduction: Absidia species have coenocytic (aseptate) hyphae and reproduce asexually by sporangia produced on sporangiophores that radiate from the mycelium. The spores are dispersed by air. Sexual reproduction occurs when compatible isolates fuse to form zygospores within a zygosporangium, characteristic of zygomycete fungi.

Ecology and distribution: They are ubiquitous in the environment worldwide, commonly found in soil, compost, decaying plant matter, and stored agricultural products. They can colonize a variety of substrates and are typically saprophytic, but some species are opportunistic pathogens.

Clinical relevance: Some Absidia species are known opportunistic pathogens in humans and animals, particularly in immunocompromised individuals, and can cause mucormycosis, a serious invasive fungal infection. Management requires rapid diagnosis and antifungal therapy, often with amphotericin B; newer azoles such as posaconazole and isavuconazole may be used in some cases.

Taxonomy notes: The genus has undergone taxonomic revision, and several species once classified as Absidia have been reassigned to other genera within Mucorales, such as Lichtheimia. The taxonomic status of Absidia species may vary among sources.