MLS 474 (Clinical Mycology) –To reveal sufficient basic science of the medically important fungi to assist you in diagnosing mycotic diseases. –To reveal sufficient clinical knowledge to raise your index of suspicion for mycotic diseases. OBJECTIVES

 Introduction to medical mycology  Fungal classification and Taxonomy  Antifungal Therapeutic Agents  Superficial Mycoses  Cutaneous Mycoses  Subcutaneous Mycoses  Systemic Mycoses  Fungal Allergies  Mushroom Poisoning and other Mycotoxins Topics

INTRODUCTION INTRODUCTION

the study of fungi, includes their genetic and biochemical properties, their taxonomy, and their use to humans as source for medicinals (e.g., penicillin), food (e.g., beer, wine, cheese, edible mushrooms), as well as their dangers, such as poisoning or infection. What is Mycology? MYCOLOGY is the study of fungi Myco- = fungi -ology = the study of

Kingdom Fungi The characteristics of fungi The characteristics of fungi Fungal classification Fungal classification Fungal life cycles Fungal life cycles

The Characteristics of Fungi Body form Body form –unicellular –filamentous (tube- like strands called hypha (singular) or hyphae (plural) –mycelium = aggregate of hyphae –sclerotium = hardened mass of mycelium that generally serves as an overwintering stage. –fruit bodies (mushrooms)

Tubular Tubular Hard wall of chitin Hard wall of chitin Crosswalls may form compartments (± cells) Crosswalls may form compartments (± cells) Multinucleate Multinucleate Grow at tips Grow at tips Hyphae

Hyphal growth Hyphae grow from their tips Hyphae grow from their tips Mycelium = extensive, feeding web of hyphae Mycelium = extensive, feeding web of hyphae Mycelia are the ecologically active bodies of fungi Mycelia are the ecologically active bodies of fungi This wall is rigidOnly the tip wall is plastic and stretches

Mode of nutrition Fungi get carbon from organic sources Fungi get carbon from organic sources Hyphal tips release enzymes Hyphal tips release enzymes Enzymatic breakdown of substrate Enzymatic breakdown of substrate Products diffuse back into hyphae Products diffuse back into hyphae Product diffuses back into hypha and is used Nucleus hangs back and “directs” Heterotrophic – 'other food‘ Heterotrophic – 'other food‘

- Saprobes : - Saprobes : feed on dead tissues or organic waste (decomposers) feed on dead tissues or organic waste (decomposers)

Fungi as Saprobes and Decomposers

– Symbionts : mutually beneficial relationship between a fungus and another organism

Fungi as Symbionts (Mutualism)

Mycorrhizae “Fungus roots” “Fungus roots” Mutualism between: Mutualism between: –Fungus (nutrient & water uptake for plant) –Plant (carbohydrate for fungus)

Lichens “Mutualism” between “Mutualism” between –Fungus – structure –Alga or cyanobacterium – provides food

–Parasites : feeding on living tissue of a host. feeding on living tissue of a host.  Parasites that cause disease are called pathogens.

Fungi as Parasites –Pathogens.

Fungi are Spore-ific!!! Spores - asexual (product of mitosis) or sexual (product of meiosis) in origin. Spores - asexual (product of mitosis) or sexual (product of meiosis) in origin. Purpose of Spores Purpose of Spores –Allows the fungus to move to new food source. –Resistant stage - allows fungus to survive periods of adversity. –Means of introducing new genetic combinations into a population

Reproduce by spores Spores are reproductive cells Spores are reproductive cells –Sexual (meiotic in origin) –Asexual (mitotic in origin) Formed: Formed: –Directly on hyphae –Inside sporangia –Fruiting bodies Amanita fruiting body Pilobolus sporangia Penicillium hyphae with conidia

Hyphal growth from spore mycelium germinating spore Mycelia have a huge surface area Mycelia have a huge surface area

Generalized Life Cycle of a Fungus

Definitions and Fungal Terminology Definitions and Fungal Terminology

CLINICAL MYCOLOGY: CLINICAL MYCOLOGY: Remains more of a descriptive art than an analytical science. Remains more of a descriptive art than an analytical science. Mold (sometimes spelled ‘mould’): is a morphological term referring to a filamentous (multicellular) fungus. Yeast is a morphological term referring to a unicellular fungus. DIMORPHIC FUNGI: This class of fungi is characterized by two forms of growth: 1. Growth as a mold with septate hyphae in their natural reservoir (e.g. soil) or when incubated at 25° C. on conventional fungal media (Sabouraud dextrose or potato dextrose agars). 2. Growth as a yeast in the tissues of an animal/person or when incubated at 37° on enriched media (Brain heart infusion agar).

A hypha (plural hyphae) is a long, branching filamentous cell. hyphae are the main mode of vegetative growth, and are collectively called a mycelium. Mycelium: the intertwined mass of hyphae that forms the mold colony. The vegetative mycelium is composed of those hyphae that adhere to the substrate and absorbs nutrients. The aerial mycelium is composed of those hyphae that grow up from the surface and support the spores. Septate: Cross-walls (septae) that divide hyphae into segments. If there are few or no cross-walls the hyphae are considered to be aseptate.

Conidia (singular = conidium): asexual spores borne externally on hyphae or on a conidiophore. Conidiophore: the specialized hyphal stalk on which conidia develop either singly or in Clusters. Conidia Conidiophore

Sporangia (singular = sporangium): spherical sack within which asexual spores (sporangiospores) form by progressive cytoplasmic cleavage. Sporangiophore - specialized hyphal stalk which bears sporangia. Sporangiospores: small spores contained within sporangia. Sporangiospores Sporangium Sporangiophore

Rhizoid: rootlike branched hyphae which anchor the mycelium to the substrate; characteristic of certain Zygomycetes (Rhizopus and Absidium). Dematiaceous Molds: the term dematiaceous refers to molds whose hyphae are pigmented. Because of the pigment, the colonies of these fungi will appear dark green, brown, or black on both the top and reverse (underside). Germ-tube: The initial hyphal outgrowth of a germinating spore or yeast; especially important for identification of Candida albicans. Pseudohyphae (or Pseudomycelium): chains of successively budding yeast cells that have complete cell walls, but have not detached from one another.