The main human diseases caused by fungi are coccidioidomycosis, histoplasmosis, blastomycosis, paracoccidioidomycosis, or South American blastomycosis, sporotrichosis, aspergillosis and systemic candidiasis. Fungi are also responsible for many dermatologic diseases (dermatomycosis) that affect the skin, the nails, the scalp, etc. On the other hand, many fungi are able to produce antibacterial substances that combat diseases. In the second world war, in German jails, Russian prisoners that accepted to eat moldy bread had less skin infection than those that refused the food. In China, moldy soy sauce has millennial past use against infections. Penicillin, a potent antibiotic, was discovered in 1928 by Alexander Fleming when he observed the antibacterial activity of fungi from the genus Penicillium.