INTRODUCTION

Mycology is the study of fungi. Fungi are extremely beneficial microorganisms. They are important in the food chain because they decompose dead plant matter, thereby recycling vital elements. Nearly all plants depend on symbiotic fungi to help their roots absorb minerals and water from the soil. Fungi are used by humans for food, and in the manufacture of food and beverages including bread, alcoholic beverages, citric acid (the basis of soft drinks), soy sauce, and some cheeses. Fungi also produce antibiotics (penicillin and cephalosporin), immunosuppressive medications, and cholesterol reducing drugs.

Fungi are eukaryotes. Their cell walls are made of chitin and they have sterols in their cell membrane. In microbiology we study two fungi, yeast and mold. Yeast are unicellular and non-filamentous. Microscopically they are oval shaped and reproduce asexually by budding. Macroscopically yeast is moist, creamy, and white and grow in colonies. Mold is multi-cellular and filamentous. The filaments are called hyphae. Mycelium is a mass of intertwined hyphae. Macroscopically mold looks fuzzy. Mold reproduces asexually via spores which can be inhaled by humans as a means of disease transmission.

Of the more than 100,000 species of fungi, only about 200 are pathogenic to humans and animals. Any fungal infection is called a mycosis. Anyone can get a fungal infection; some fungal infections like skin, nail, and vaginal yeast infections are common. Fungi are common in the environment, and most people breathe in or come in contact with fungal spores every day without getting sick. However, in people with weakened immune systems, these fungi are more likely to cause an infection because many fungi are opportunists. People at a higher risk for developing fungal infections include people living with HIV/AIDS, cancer patients, organ transplant patients, hospitalized patients, stem cell transplant patients, and people taking medications that weaken the immune system. The number of cases of most human fungal diseases is not known, most fungal diseases are not reportable to the CDC.