Achorion Remak

ACHORION REMAK, a genus of fungi from the group of 'imperfect' fungi (Fungi imperfecti, see Ascomycetes), closely related to the genus Oospora Wallr., which some authors (Saccardo) include it in. The A. R. genus includes the fungi that cause favus in humans and animals. The causative agent of human favus, A. Schonleini Remak (Oospora porriginis Mont et Berk), discovered by Schönlein in 1839, was the first pathogenic microorganism known to medical science. This fungus is distinguished by extreme polymorphism. The scales (scutula) from the hairy part of the head of a person affected by favus contain various elements of the fungus: oval and angular spores, single and in chains, dense mycelial weaves of varying thickness and content. A. R. is easily isolated in pure cultures by Krahl's method. The optimum temperature for its development is 35°. Requiring abundant nitrogen nutrition, A. R. grows well on agar with 3% maltose and 2% peptone, forming waxy yellowish cakes with radial folds and a central elevation. In cultures with aerial mycelium, it produces small single-celled exospores and spindle-shaped multicellular spores, while in the substrate it produces oidia (endospores of medical authors). It also forms chlamydospores, especially on potatoes. All species of A. R. are extremely close to each other and in cultures are almost indistinguishable even by specialists. Plaut distinguishes two main species—Achorion Schönleini with the closely related Oospora (Achorion) canina Sabrazes (favus of dogs) and Achorion Quincke—mange (favus of mice) with the closely related Achorion gallinae Schutz (favus on chicken combs). Intermediate species are Achorion violaceum Bloch (on mice and humans) and Achorion gypseum Bodin (on humans and animals).