2. Mycology Study of fungi Greater than 100,000 fungal species
Only ~200 human/animal pathogen FUNGI Eukaryotes: Yeasts and molds
Cell wall Chitin Cell membrane - ergosterol Chemoheterotrophs
Require organic compounds for carbon and energy Food industry:
bread, alcohol, edible fungi (mushrooms), cheeses Some are deadly
Adapted to environments hostile to bacteria pH 5 High osmotic
pressure Low moisture Complex carbohydrates (ex. Lignin from wood)
Less nitrogen
3. Yeast Unicellular fungi Spherical Facultative anaerobe
Reproduce budding or fission Budding Yeast Ex. Saccharomyces Uneven
division Bud forms on outer surface Parent nucleus divides One
nucleus migrates into bud Cell wall forms, bud breaks away Fission
Yeast Ex. Shizosaccharomyces Binary fission identical daughter
cells
4. Molds and Fleshy Fungi Multicellular Aerobic Composed of
hyphae Long filaments of cells joined together Grow by elongating
at ends Fragments break off to form new hyphae Hyphae: Vegetative
Part that absorbs nutrients Aerial Projects above medium Bears
reproductive spores
5. Fungal Reproduction Molds (multicellular fungi) Asexual
reproduction Fragmentation Hyphae break off to form new molds
Spores Asexual spores Form by mitosis, detach from parent,
germinate to form new hyphae identical to parent Sexual
reproduction Sexual spores Formed by fusion of nuclei from two
opposing mating strains Detach from parent structure Germinate into
new mold Contain genes from both parent fungi
6. Asexual Spores Examination of spores aid clinical
identification of fungal infection Two Types Sporanigospore Formed
in sac (sporangium) at end of aerial hyphae (sporangiophore) Ex.
Rhizopus Hundreds of spores in a single sac
7. Asexual Spores: Condiospore Also called Conidia (dust:
detach easily and float like dust!) Not enclosed in a sac Seen as
chains at end of conidiophore Ex. Aspergillus
8. Other Conidia: Arthoconidia and Blastoconidia Arthoconidia =
conidiospores formed by fragmentation of a hypha into single cells
Ex) Coccidioides immitis Blastoconidia = conidiospores formed by
buds coming off the parent cell Ex) yeasts like Candida albicans
Other fungi: Cryptococcus (yeast stage)
9. Spore Formation Hyphae forms conidia (or sporangia) Spores
disseminate in air Inhalation irritants allergens also spores in
respiratory system source of infection
11. Mycoses Fungal Infections Usually chronic, fungi grow
slowly Treatment difficult Fungi are eukaryotes Antifungals can
affect human cells Serious kidney, liver failure Types of Mycoses
Cutaneous Subcutaneous Systemic Opportunistic
12. Cutaneous Mycoses Fungal infection of skin, hair, nails
Dermatophytes Cause only cutaneous infections Secrete keratinase to
degrade keratin Trichophyton, Epidermophyton, Microsporum Need to
remember those names and what they cause
13. Tinea pedis: Athletes Foot Caused by Trichophyton
Multicellular hyphae with asexual spores (arthroconidia) Results in
scaling, flaking, itching of feet Transmission Contagious can be
spread through contact Reservoirs = warm, damp areas Prevention
Keep skin clean and dry Wear sandals in community pools and showers
Wash hands after touching other people/ animals that may carry
fungal infections Treatment Topical antifungals Trichophyton rubrum
Do not need to remember treatments unless told
14. Tinea capitis (ringworm of scalp) Caused by Microsporum
genus Grows as multicellular hyphae asexual spores (conidiospores)
Found in soil and on animals Results in inflammation, scarring,
permanent hair loss Transmission = touching infected human or
animal, touching infected objects Treatment = terbinafine
hydrochloride (lamisil) ingestion
15. Subcutaneous Mycoses Infection beneath the skin More
dangerous than cutaneous Usually from soil dwellers invading
puncture wounds Ex) Sporotrichosis: Sporothrix schenkii Most common
subcutaneous mycosis Dimorphic: 25oC hyphae, spores 37oC yeastlike,
budding Transmission = handling of soil or plant material Symptoms
= small ulcer where it entered Spread along lymph vessels creating
more ulcers Treatment = potassium iodide (ingestion),
itraconazole
16. Systemic Mycoses Fungal infection affecting internal organs
Soil dwelling fungi Initiated by inhaling spores Infection in lungs
Spreads to other parts of body Histoplasmosis: Histoplasma
capsulatum Dimorphic = filamentous in soil, yeast-like morphology
in tissue lives, multiplies in macrophages Symptoms: mainly mild
respiratory infection Treatment: if severe, intravenous
Itraconazole
17. Histoplasmosis: geographic distribution Areas of moist
soils are good for H. capsulatum growth more airborne spores
18. Systemic mycoses: Coccidioidomycosis Valley Fever
Coccidiodes immitis Dry, alkaline soils of American SW, S. America
and Mexico Dimorphic = filamentous in soil; thick-walled spherule
filled with spores in tissue Symptoms = Chest pain, fever,
coughing, weight loss Diagnosis = Identification of spherules in
tissue/fluids Treatment = Most recover without treatment
19. Systemic Opportunistic Mycoses Opportunistic mycoses Fungal
infection occuring in immunocompromised human/animal Ex)
Pneumocystis pneumonia Pneumocystis jirovecii Few or no symptoms in
healthy lungs Symptoms in immune compromised Primary indicator of
AIDS Symptoms = fever, cough, difficulty breathing Diagnosis =
detection of cysts in lung tissue/fluid Treatment =
trimethoprimsulfamethoxazole
20. Systemic opportunistic mycoses Ex) Aspergillosis
Aspergillus fumigatus Transmission = airborne spores from soil and
compost Most people inhale Aspergillus spores every day Destroyed
by healthy immune systems Pathogenesis = germinate into hyphae in
alveoli lesions Symptoms = fever, bloody cough, chest pain
Diagnosis = lung tissue biopsy Treatment = amphotericin B,
voriconizole
21. FUNGAL PNEUMONIA Ascomycota Sac Fungus Aspergillus
Organism: Aspergillus fungus Frequently found in compost heaps, air
vents, pillows and airborne dust. Transmission: Inhalation of
spores is primary cause of Aspergillosis. Course: Usually affects
open spaces such as cavities that have formed in the lungs from
preexisting lung diseases. Shows up as a tangled mass of fungus
fibers, blood clots, and white blood cells. Fungus ball gradually
enlarges, destroying lung tissue, but usually doesnt spread. Less
often can become very aggressive and rapidly spread throughout the
lungs and often through the bloodstream to the brain and kidneys
(immune compromised). Diseases of the Respiratory System
22. Opportunistic Normal Flora Candida albicans Part of normal
flora of mouth, skin, intestine and vagina Opportunistic
candidiasis - Oral thrush: whitish velvety sores of the mouth and
tongue - Vaginitis (yeast infection) Candida blastoconidia (asexual
spores) SEM Oral thrush in an infant