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58 Cards in this Set

  • Front
  • Back
Distinguishing characteristics of fungi
Absorptive Nutrition
LACK chlorophyll
Maintain cell wall (3 layers) throughout life cycle
ERGOSTEROL
Yeasts vs. Moulds
YEASTS -- unicellular, round, budding or fission
MOULDS -- multicellular, filamentous, spores or conidia
Dimorphic growth
Grows as BOTH mould and fungi

MOULD -- 28-30 degrees C
YEAST -- 37 degrees C
EXCEPTION -- Coccidioides (form spherules)
Primary genus of CAPSULAR fungi
Cryptococcus
Superficial mycoses
Piedras
Tinea Nigra
Pityriasis Versicolor (most common)
Pityriasis Versicolor
Caused by Malassezia (globosa, furfur)
Suntan lotions (organisms are LIPOphilic)
Common in adolescents and YOUNG adults

Note: Malassezia also causes folliculitis in AIDS pts.
Microscopic appearance of M. Furfur
Spaghetti and Meatballs
Most common fungal disease
Dermatophytosis (ringworm)
Three genera of dermatophytes
Microsporium
Trichophyton (distinguished by vitamin requirements)
Epidermophyton floccosum (does NOT cause scalp disease)
Tinea Capitis
Scalp, eyebrows, eyelashes
Associated with POOR HYGIENE
Microsporium and Trichophyton, NOT Epidermophyton

Ectothrix -- invasion of follicle, but NO hair penetration
Endothrix -- penetration of hair
Tinea Corporis
Classic ringworm
Glabrous (smooth, no hair) skin
Tinea Cruris
Jock itch
Epidermophyton floccosum
MUST be distinguished from Candida infection
Tinea pedis
Ball of feet & interdigital areas
Trichophyton and Epidermophyton
Acute form is better
Id Reaction
Vesicles found distant from the site of infection
Often associated with Tinea Pedis
Tinea unguium
Nail infection
Chronic
Tinea barbae
Bearded area of face
Similar to T. capitis, BUT much more inflammatory

Relieved by removal of beard
Mycosel culture medium
Contains cycloheximide and chloramphenicol
Inhibits bacteria
General treatment for dermatophytosis
Topical -- azoles, tolnaftate, salicylate
Treatment for recalcitrant onychodermatomycosis
Griseofulvin and Terbinafine (Lamisil)
Sporotrichosis
("Rose-Handler's Disease")
Sporothrix schencki

Dimorphic ("rose petal" mould, "cigar" yeasts)
ASTEROID BODY is almost pathognomonic
Found in soil, wood, moss
Can be inhaled (AIDS)

Common form is lymphocutaneous
ASCENDS up lymphatics (stops @ shoulder)
Treatment for Sporotrichosis
Itraconazole
Amp B for life-threatening disease
Saturated solution of KI for cutaneous disease
Chromoblastomycosis
(Verrucous Dermatitis)
Pigmented fungi (melanin)
Hyperplasia limited to SUBcutaneous areas
"Muriform sclerotic cells" -- COPPER PENNIES

Treatment same as Phaeohyphomycosis (surgery, amp B)
Phaeohyphomycosis
All other forms of what once was chromoblastomycosis
NO muriform cells (NO "copper pennies")
Disease usually in feet and legs
Some agents can infect brain

Treatment -- Surgery, Amp B, Itraconazole
Agents of Phaeohyphomycosis that can spread to brain
Cladophialophora BANTIANA
BIPOLARIS
Eumycotic Mycetoma
Soil fungi through skin
Destruction of bone and muscle

TRIAD -- tumefaction, draining sinus tracts, granules
Candida species that does NOT form pseudohyphae
Candidiasis Glabrata
Diseases caused by Candida
Vaginitis (most common)
Oral Thrush (2nd most common)
Cutaneous & systemic Candidiasis
Candida species that is most virulent in cancer pts.
Candida tropicalis
Germ tube test
Presumptive test for Candida
Germ tube within 2 hours indicative of C. Albicans
Defect predisposing to mucocutaneous candidiasis
Functional PMNs, but low CD4
Defect predisposing to systemic candidiasis
Neutropenia
Cryptococcosis
Cryptococcus Neoformans

CAPSULE -- galactoxylomannan polysaccharide
Pigeon droppings (needs high N content)
Meningitis is most common complication
Can disseminate to skin and bone
Assoc. with collagen diseases
INDIA INK
Fibrotic changes -- X-ray MAY not be useful

Treatment -- Amp B & fluconazole
Subcutaneous mycoses
Sporotrichosis
Phaeohyphomycosis
Eumycotic Mycetoma
Chromoblastomycosis
Yeast Infections
Candidiasis
Cryptococcosis
Systemic fungi
Histoplasma
Paracoccidioides
Blastomcyes
Coccidioides
Systemic fungus with MORE frequent calcification
Histoplasmosis
Fungi with which caseation is LESS common
Paracoccidioides
Blastomycosis
Histoplasmosis
("Spelunker's disease")
Histoplasma capsulatum

Worldwide
In U.S.: Miss./Ohio River Valleys, Midwest, Va., Md.
Identify by micro/macroconidia (tuberculated)
Important problem in AIDS
Bird droppings (high N content)
Infections follow inhalation of spores/mycelium
Can mimic Tb
Grow INTRACELLULARLY in histiocytes
More frequent calcification -- COIN LESIONS

Treatment -- Amp B, Itraconazole
Only true intracellular fungal pathogen
HISTOplasmosis
Blastomycosis
Blastomyces Dermatitidis

East of Miss., Miss./Ohio River Valleys
Inhaled microconida (soil enriched with wood [beaver DAMS])
Disease more frequently seen in DOGS
Can disseminate to skin and bone (skin > bone)

Budded yeast with a Broad Based Bud (BBBB)

Treatment -- Amp B, Itraconazole, Ketoconazole
Coccidioidomycosis
(San Joaquin Valley Fever)
Coccidioides Immitis & C. Posadasii

Southwest USA, Northern Mexico, South America
RACE DEPENDENT: Filipinos > Blacks > Whites
Septated, filamentous fungus in desert soil
SPHERULES filled with ENDOSPORES
Allergic reactions -- Desert Bumps, Desert Rheumatism
Can show coin lesions, BUT X-ray may not be helpful
Disseminated -- reactivation due to steroid therapy (can cause meningitis)

Treatment -- Amp B INITIALLY, then fluconazole/itraconazole
Paracoccidioidomycosis
Paracoccidioides BRASILensis
Central and South America

Identify by microconidia (PILOT's WHEEL)
Causes oral lesions
Primary pulmonary disease (disseminates)

Treatment -- Amp B with sulfa drugs, Itraconazole
Places Histoplasmosis can disseminate
Spleen, Liver, Adrenals, BM, eye orbit, lymph nodes
Places Paracoccidioidomycosis can disseminate
Spleen, Intestines, Liver, Skin
Penicillosis
Penicillium Marneffei

Southeast Asia
Causes of Zygomycosis
Rhizopus
Absidia
Mucor
Polyenes
FungiCIDAL
Bind ergosterol, disrupting membrane (form pores)
Ex. -- Amp B, Nystatin, Natamycin (ophthalmic only)

Resistance -- lack of ergosterol in membrane
Amphotericin B
("Amphoterrible")
FungiCIDAL polyene that binds ergosterol

Agent of choice against systemic disease (life threatening)
I.V. (oral formulation has limited use)
SIDE EFFECTS -- nephrotoxicity

Lipid formulation decreases toxicity
-- Does NOT increase efficacy --
Aministration routes for Nystatin
Used topically and orally (NOT absorbed well)
Azoles
Generally, NOT fungicidal
Agents of choice for NON-life threatening diseases
Inhibit C-P450 dependent demethylation of lanosterol
PREVENT ergosterol synthesis
Ex. -- Fluconazole, Itraconazole, Ketoconazole

Resistance -- multiple mechanisms, upregulation of MDR pores
Allylamines
Cidal for some organisms
Used primarily for DERMATOPHYTOSIS

INHIBIT SQUALENE EPOXIDASE

Generate toxic accumulation of squalene
Ex. -- Naftifine, Terbinafine

Resistance -- target mod., poor penetration, overprod. of target
Candins
Drugs used primarily for CANDIdiasis

Inhibit synthase of cell wall
Actual targets are synthase regulatory proteins
Ex. -- Caspofungin, Micafungin

Resistance -- modified targets

NOT effective against Crypto, Zygomycetes, Fusarium
Nucleoside Analog
Inhibits nucleotide synthesis
Converted to 5-FLUOROURICIL in cytoplasm

Resistance -- developed rapidly
Nikkomycins
Anti-fungals that work against Coccidioidomycosis
Kirby-Bauer Assay
Agar is impregnated with antibiotics
Scale relates clearance to min. inhibitory conc. (MIC)
Anamorph
ASEXUAL form in fungal life cycle
Conidia
ASEXUAL spores of fungus
YEAST that causes a fibrotic response
(May be X-ray transparent)
Cryptococcus
(also can be case with Coccidioides)