MLS 474 (Clinical Mycology)

1. MLS 474 (Clinical Mycology) OBJECTIVES • 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.

2. Topics • 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

3. INTRODUCTION

4. What is Mycology? MYCOLOGY is the study of fungi Myco- = fungi -ology = the study of 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.

5. Kingdom Fungi • The characteristics of fungi • Fungal classification • Fungal life cycles

6. The Characteristics of Fungi • 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)

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

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

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

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

11. Fungi as Saprobes and Decomposers

12. Symbionts : mutually beneficial relationship between a fungus and another organism

13. Fungi as Symbionts (Mutualism)

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

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

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

17. Fungi as Parasites –Pathogens.

18. Fungi are Spore-ific!!! • Spores - asexual (product of mitosis) or sexual (product of meiosis) in origin. • 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

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

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

21. Generalized Life Cycle of a Fungus

24. Definitions and Fungal Terminology

25. Mold (sometimes spelled ‘mould’): is a morphological term referring to a filamentous (multicellular) fungus. CLINICAL MYCOLOGY: Remains more of a descriptive art than an analytical science. 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 septatehyphae 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).

26. 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 hyphaeinto segments. If there are few or no cross-walls the hyphae are considered to be aseptate.

27. 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

28. 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

29. 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. 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).