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151 Cards in this Set

  • Front
  • Back
Which pathogenic fungi are do not come from the environment?
Candida and Malassezia, which are part of the normal flora
Which fungus is responsible for wiping out frogs?

How does this fungus infect?
Chytridiomycosis caused by Batrachonchytrium dendrobatidis.

Uses keratin as nutrient --> hyperkeratosis + excessive shedding
Batrachochytrium dendrobatidis
Fungus that causes chytridiomycosis = wiping out the global amphibian species. Endemic among African clawed frog.

Uses keratin as nutrient --> hyperkeratosis + excessive shedding
Stem Rust
Aggressive wheat fungus that is putting world's wheat crop in danger.
Fungi cell structure
1. plasmalemma: ergosterol

2. cell wall: chitin (N-acetyl glucosamine polymer)

3. mannans and glucans = polysaccharide capsule
Sabouraud's medium
selective for fungi b/c of acid pH and high sugar content
Non-infectious syndromes of fungi
Hypersensitivity pneumonitis

Mycetismus/Mushroom poisoning

Hypersensitivity pneumonitis
Caused by inhalation of material contaminated by a variety of molds

acute: 4-8 hrs post-exposure to intermittent high levels --> fevers, chills, cough, SOB

chronic: low level chronic exposure --> insidious onset of cough, SOB, weight loss
Acute hypersensitivity pneumonitis
acute: 4-8 hrs post-exposure to molds intermittent high levels --> fevers, chills, cough, SOB
Chronic hypersensitivity pneumonitis
chronic: low level chronic exposure to molds --> insidious onset of cough, SOB, weight loss
Types of hypersensitivity pneumonitis
Farmers lung
Malt-workers lung
Maple bark-strippers lung
Suberosis/Cork workers lung
Cheese-washers lung
Ventilator pneumonia (humidifiers, air conditioning)

Most occupational diseases
Farmers lung
Type of hypersensitivity pneumonitis

Late winter/early spring when farmers using moldy (Actinomyces) stored hay to feed livestock

Remarkable predominance of non-smokers
Mushroom poisoning

Amanita phalloides (death cap mushroom) causes 95% of North American fatalities

Majority of cases accidentally and in kids
Amanita phalloides
"Death cap" mushroom responsible for 95% North American fatalities from mushroom poisoning.

Primarily in cool coastal regions of West Coast

Alpha-amantin = principle toxin, RNA pol II inhibitor, heat stable and water insoluble (cooking no use)

Triphasic disease
principle toxin of Amanita phalloides, RNA pol II inhibitor, heat stable and water insoluble (cooking no use)
Phase I: 6-24 hrs post-exposure, profuse watery diarrhea with nausea and vomiting

Phase II: quiescent

Phase III: 3-6 days post-exposure, hepatic and renal failure with 50-90% mortality
Amanita phalloides poisoning
Ingestion of fungal toxins in foods damaged by molds

e.g. ergot alkaloids, aflatoxins, tricothecene toxin (T-2)
Ergot Alkaloids
Made by Claviceps purpurea when it infects rye

Converts rye seed into a sclerotium made of fungus

Mycotoxicosis --> alpha adrenergic blockade with peripheral vasoconstriction --> gangrene

aka St. Anthony's fire in Middle Ages
Contaminated feed by Aspergillus fumigatus

Mycotoxicosis = coumarin derivatives produced --> hemorrhages + liver necrosis

Potent liver carcinogen

Present in peanut products
Tricothecene toxin (T-2)
Made by Fusarium sporotrichoides that infects cereal grain left in fields

Causes alimentary toxic aleukia

Manifests as leukopenia + mucositis
Superficial mycoses
Skin (limited to stratum corneum): pityriasis versicolor, tinea nigra

Hair (limited to cuticle): black piedra, white piedra
Host defense against cutaneous mycoses
Fatty acid content of skin

Epithelial turnover

Normal bacterial flora
Pityriasis versicolor: clinical manifestations
Malassezia furfur, lipophilic, dimorphic yeast

Dry, scaly, hyperpigmented or hypopigmented lesions on upper torso, arms, abdomen

Rare systemic disease (fungemia) in infants on IV intralipid therapy and peritonitis in patients on chronic ambulatory peritonitis.
Malassezia furfur
Pityriasis versicolor (cutaneous mycosis)

Lipophilic, dimorphic yeast that is part of normal flora, found in areas rich in sebaceous glands
Pityriasis versicolor: transmission/epidemiology
Part of normal flora, found in areas rich in sebaceous glands

Transmitted by direct contact

Increased incidence in tropics, athletes, renal transplant patients, AIDS
Pityriasis versicolor: lab dx
KOH prep: classic spaghetti and meatballs (combined yeast and hyphal elements)

Fluoresce yellow under Wood's light (UV lamp)
Pityriasis versicolor: treatment/prevention
Tx: selenium sulfide with repeat application to avoid relapse

Depigmented patches may remain for months, esp in winter
Tinea nigra: clinical manifestations
Hortae werneckeii, a dimorphic melanin-containing fungus

Flat brown to black macular lesions of palms and soles
Hortae werneckeii
Tinea nigra (superficial mycosis)

dimorphic melanin-containing fungus
Tinea nigra: transmission/epidemiology
Found in soil, transmitted by injury
Tinea nigra: lab dx
KOH prep: darkly pigmented yeast cells and hyphal fragments

Culture: black colonies
Spaghetti and meatballs on KOH prep
Malassezia furfur: pityriasis versicolor
Black piedra: clinical manifestations
Piedraia hortae present in perfect state when colonizes hair shaft

Hard, brown to black nodules on infected hair shaft house asci containing ascospores with dark septate hyphae
Piedraia hortae
Black piedra
Black piedra: lab dx
Microscopic exam of hairs in KOH prep reveals dark pigmented nodules
White piedra: clinical manifestations
Trichosporon species, dimorphic fungus

Cream-colored, soft nodules on hair shaft

Can cause disseminated trichosporonosis, mainly in neutropenic and immunocompromised
Trichosporon species
White piedra
White piedra: lab dx
Microscopic exam of hairs in KOH prep reveals white to light brown nodules

Grows on all media except if with cycloheximide. Grows as septate hypae with arthroconidia with septate hyphae
Caused by Trichosporon species and Blastoschizomyces capitatus.

Risk factors = neutropenia + corticosteroids

Sx: fungemia with cutaneous and ocular lesions
Cutaneous mycoses
Dermatophyte infections usually restricted to skin, hair, nails

Possess keratinases

Differ from superficial mycoses by evoking inflammatory response
Epidermophyton floccosum
Tinea pedis

Hyphal form in culture has large club-shaped macroconidia
Microsporum canis
Fluorescent tinea capitis

In culture, thick walled, spindle-shaped, spiny macroconidia
Tinea barbae
Trichophyton verrucosum

Inflammatory vesicopustular eruptions, usually unilateral (side toward cow), mistaken for Staph aureus
Trichophyton verrucosum
Tinea barbae
Tinea capitis
Primarily by Trichophyton tonsurans (does not fluoresce) --endothrix

Also by Microsporum canis (fluoresces) -- ectothrix

Dry, ringlike, scaly, itchy, erythematous lesions in scalp, may present as areas of alopecia (ectothrix)
Spores surround shaft due to destruction of cuticle

May fluoresce or not

Usually presents as areas of alopecia

Gray patches due to hair breaking off just above scalp
spores inside shaft

Trichophyton tonsurans

Hair breaks off at follicle leaving black dot

Kerion: boggy, purulent patches of alopecia, inflammatory
Trichophyton schoenleinii

Thick yellow crust on scalp made of hyphal elements

Hyphae course through the hair shaft with air spaces

Most serious of hair dermatophytes, may lead to alopecia with scarring
Tinea cruris
Trichophyton rubrum

Scalloped, erythematous, scaling border in groin area (does not involve scrotum)

aka jock itch
Trichophyton rubrum
Tinea cruris

Trichophyton tonsurans
Tinea capitis (non-fluorescent), endothrix
Microsporum canis
Fluorescent tinea capitis (ectothrix)
Onychomycosis: epidemiology
Men >> women

Toenails >> fingernails

Prevalence increases with increasing age
Onychomycosis: etiology
Dermatophytes = majority
Trichophyton rubrum
Epidermophyton floccosum
Trichophyton mentagrophytes


Non-dermatophyte molds (Aspergillus, etc)
Distal subungal onychomycosis
Trichophyton rubrum
Proximal subungal onychomycosis
Classic nail sign of HIV infection
White superficial onychomycosis
Trichophyton mentagrophytes

Candida onychomycosis
Limited to patients with chronic mucocutaneous candidiasis
Differentiating psoriasis from onychomycosis
psoriasis has sharply defined pitting of nail plate surface
Mycetoma: clinical manifestations
aka Madura foot

subcutaneous mycosis

inoculation due to injury (esp if barefoot)

edema, induration, abscesses, draining sinuses with granules, most commonly of foot

may be bacterial or true fungi (Eumycotic mycetoma)

Nocardia braziliensis if Central/South America (actinomycotic)

Madurella mycetomatis if Africa (eumycotic)
Eumycotic mycetoma dx
examination of granules (look like miniature colonies)
Chromoblastomycosis: clinical manifestations
caused by variety of dermatiaceous fungi (have black/brown pigment in cell wall)

slow development of verrucous (warty) lesions that progress to cauliflower appearance
Slow development of verrucous (warty) lesions that progress to cauliflower appearance
Chromoblastomycosis: lab dx
Medlar bodies/sclerotic bodies/copper pennies
Copper pennies/Medlar bodies/Sclerotic bodies
Sporotrichosis: clinical manifestations
Sporothrix schenkii, dimorphic

nodular and ulcerative lesions that develop along lymphatics

sphagnum moss, rose thorns, hay bales, cats in Rio de Janeiro, Brazil
Alcoholic rose gardener with nodular and ulcerative lesions along arm
Sporotrichosis - Sporothrix schenkii
Volunteers at a haunted house that handled hay bales present with nodular and ulcerative lesions along the arm
Sporotrichosis - Sporothrix schenkii
Sporotrichosis: lab dx
Asteroid bodies aka Splendore-Hoeppli phenomenon

budding cigar-shaped yeast at 37 degrees but delicate hyphae with conidia in rosette pattern at 25 degrees (dx by converting mycelial to yeast phase)
Rhinosporidiosis: clinical manifestations
Rhinosporidium seeberi

painless, pedunculated polyps developing in nasal area
Painless, pedunculated polyps developing in nasal area
Rhinosporidiosis -- Rhinosporidium seeberi
Rhinosporidiosis: epidemiology
India and Sri Lanka
Lobomycosis: clinical manifestations
Loboa loboi (Lacazia loboi)

Keloidal nodules of face, ears, and UL
Keloidal nodules of face, ears, and UL
Lobomycosis -- Loboa loboi (Lacazia loboi)
Lobomycosis: lab dx
Histology reveals 10-15 um yeasts in long chains
Caused by dermatiaceous fungi

Disseminated disease in immunocompromised
Histoplasmosis: clinical manifestations
Inhale conidia (spores) of Histoplasma capsulatum

Calcified granulomas in liver and spleen

Mostly asymptomatic in healthy

Chronic pulmonary and progressive disease in immunocompromised or b/c large inoculum
Histoplasmosis: epidemiology
Ohio and Mississippi River Valleys, Virginia, Maryland, Eastern Seaboard

Bird (starlings, chickens) and bat droppings
Histoplasma capsulatum
Small budding yeast inside macrophage

Cleaning chicken coop
Histoplasmosis: chronic pulmonary
Older white males with chronic pulmonary disease

Resembles TB

Upper lobe infiltrates on CXR often with cavity formation
Histoplasmosis: mediastinal fibrosis
Caused by overly exuberant immune response resulting in fibrous proliferation

May progress to constrict airways

Responds poorly to antifungal or surgery
Disseminated histoplasmosis
Due to defects in cell-mediated immunity

Acute disseminated: defective T-cell, hematologic malignancies, corticosteroids, AIDS, transplant recipients, infants --> hepatosplenomegaly and pancytopenia

Chronic disseminated: gradual onset of fatigue, weight loss with less organomegaly
Histoplasmosis: lab dx
Complement fixation


Urine and blood antigen detection by RIA

Direct stains of buffy coat

Delicate septate hyphae with tuberculate macroconidia
Histoplasma capsulatum var duboisii

Huge giant cells filled with yeast

Skin lesions = painless, warty dome-shaped papules, may ulcerate, subQ lesions --> cold abscesses

May result in progressive disseminated form (fevers, lymphadenopathy, hepatosplenomegaly)
Blastomycosis: clinical manifestation
Inhalation of conidia (spores) of Blastomyces dermatitidis

Symptomatic infection common with pulmonary sx (chest pain, sputum production, fever). Pulmonary infxn may be acute with ARDS with heavy inoculum, self-limited pneumonitis, or chronic disease. Upper lobe alveolar infiltrates. No cavitary lesions.

Progressive disseminated may involve:
skin -- cutaneous lesions are verrucous (warty) or ulcerated

bone -- osteomyelitis

genitourinary tract -- prostatitis,

CNS -- epidural/intracranial abscesses, chronic meningitis
Middle aged white male with extensive outdoor occupation/recreational exposure
Blastomycosis: epidemiology
Ohio and Mississippi River Valley, Missouri and Arkansas River basins

Most freq Kentucky, Arkansas, Mississippi, North Carolina, Tennessee, and Louisiana

Also in Wisconsin, Minnesota, Illinois, Virginia (Franklin)

Imp veterinary disease in sporting dogs and horses. Esp raccoon hunters and their dogs.

Assoc w/beaver lodges and canoe trips (outdoor recreation)
Blastomycosis: lab dx
Antigen detection test for urine (also BAL, CSF, serum)

ID broad-base budding yeast in tissue biopsy or purulent material or by culture

Culture ID of thermal dimorphism (mold at 25, yeast/pyriform microconidia at 37)
KOH prep ID broad-base budding yeast
KOH prep ID yeast cells in long chains
Paracoccidioidomycosis: clinical manifestations
Paracoccidioides brasiliensis -- dimorphic fungus with multiple buds (pilots wheel)

acute or chronic pneumonia

may disseminate to skin, LN, adrenal glands, spleen, and liver

most typical are oral, nasal, and facial nodular-ulcerative lesions
Paracoccidioidomycosis: epidemiology
Central and South America, especially Brazil, Venezuela, Columbia

Males 9x >> females b/c estradiol inhibits mycelia to yeast conversion
Males 9x >> women
Yeast with multiple buds in pilots wheel configuration
Paracoccidioidomycosis: lab dx
serologic tests for both yeast and mycelial antigens

KOH prep showing pilots wheel

Culture showing temperature conversion from slow-growing white mold at 25 degrees to pilots wheel yeast at 37 degrees
coccidioidomycosis: clinical manifestations
Coccidioides immitis -- dimorphic, highly infectious in mycelial phase, non-infectious parasitic phase as characterstic spherules

inhalation of arthrospore (highly infectious) -- extremely small inoculation needed

largely asymptomatic

40% clinical pulmonary disease but causes 30% CA-pneumonia in Arizona -- acute pneumonitis, hilar adenopathy, chronic progressive pneumonia, miliary, coccidioma, cavitary disease

Disseminated in 1% but #1 cause of death in Arizona AIDS pts

Primary infection may be assoc w/hypersensitivity rxn (erythema nodosum + arthralgias) = Valley Fever/miners bumps
Causes 30% of community-acquired pneumonia in Arizona
Coccidioides immitis
#1 cause of death in Arizona AIDS patients
disseminated Coccidioides immitis
Coccidioidomycosis: epidemiology
Southern California, esp San Joaquin Valley, New Mexico, west Texas, Arizona (likes semi-arid climate)

marked increased dissemination in African Americans, Filipinos, pregnancy, immunosuppressed, AIDS in Arizona
Desert flora
coccidioides immitis
Volunteers go to Mexico and return with flu-like symptoms
Coccidioidomycosis -- Coccidioides immitis
Coccidioidomycosis: lab dx
KOH prep shows characteristic spherules

rising eosinophilia
Coccidioidomycosis skin test
measures delayed hypersensitivity, excellent prognosticator

if positive, means you won't disseminate

if negative, means you probably will disseminate
African-Americans, Filipinos, pregnant, AIDS patients in Arizona @ risk
Disseminated Coccidioidomycosis
Facial ulcerative lesions and submandibular adenopathy
Valley fever

hypersensitivity reaction -- erythema nodosum and arthralgias
Earthquake in California
Candida glabrata
Increasing cause of Candida blood stream infections, esp > 60 y.o.

Intermediate fluconazole resistance b/c drug efflux

May cause breakthrough infections on voraconazole

Use capsofungin
Candida krusei
Most common in leukemia patients on fluconazole prophylaxis

Altered CYP450

Candida lusitaniae
amphotericin B resistant, sensitive to azoles
Candida parapsilosis
forms extensive biofilms

related to intravascular cathether infections (remove catheter)
Cutaneous candidiasis
involves warm, moist skin folds (intertriginous areas)

erythematous, macerated skin w/vesiculopustular satellite lesions

predisposition: ABX, steroids, BCP, pregnancy, diabetes

thick, white, vaginal discharge with burning/itching
Oral thrush: epidemiology
recent ABX
denture wearers
inhaled corticosteroids
Oral thrush: clinical manifestations
creamy, curd-like patches

acute atrophic

chronic atrophic (denture wearers)

angular chelitis
Oropharyngeal candidiasis in HIV/AIDS
Esophageal sx + oral Candida = 90-100% PPV for esophageal disease

Esophageal sx w/o oral Candida = 96% NPV for esophagea disease (is GI issue)
Chronic mucocutaneous candidiasis
severe chronic cutaneous (skin+nails) and mucosal infxns (lifelong)

specific problem with cell-mediated immunity against Candida

almost never develop systemic/disseminated disease

assoc w/thymomas, hypoparathyroidism, hypoadrenalism, hypothyroidism

some pts have circulating autoantibodies
associated with indwelling bladder catheter

very common, don't treat! usually respond to catheter removal

rarely leads to candidemia
high mortality

often related to central venous catheters, peripherally inserted central catheter -- prompt removal improves outcome

may manifest as failure to thrive w/persistent leukocytosis esp in ICU patients
Disseminated candidemia at risk population
HIV/AIDS patients, immunocompromised
hepatosplenic candidiasis
in patients receiving intensive chemotherapy with profound neutropenia

results in hepatomegaly, elevated alk phos, leukocytosis, multiple nodular densities in liver and spleen on CAT scan
Dx candidiasis
KOH or gram stain demonstrates budding yeast with pseudohyphae

C. albicans ID by formation of germ tubes
Budding yeast with pseudohyphae
Candida species
Cryptococcosis: clinical manifestations
inhale yeast cells

acute and chronic pneumonia

#1 cause meningitis in AIDS patients (slow onset CNS symptoms that progress to chronic meningitis)

skin lesions often misdiagnosed as molluscum contagiosum
capsular mucopolysaccharide inhibits phagocytosis

pigeon poop
Pigeon poop
Cryptococcus neoformans
Cryptococcosis: lab dx
detect polysaccharide antigen by latex agglutination or EIA

India ink prep for rapid dx (fried egg)

mucicarmine stain of tissue (will stain capsule)

brown colonies on bird seed agar
Crescent sign on CXR
Aspergilloma (fungus ball)

hemoptysis is common sx
Aspergillosis: clinical manifestations
in immunocompromised:

allergic bronchopulmonary aspergillosis -- episodic asthma, brown mucous plugs, eosinophilia, elevated IgE


invasive aspergillosis -- severely immunocompromised, angioinvasive fungus (infarction), rapidly fatal dissemination
ground glass infiltrate/halo sign and crescent sign
invasive aspergillosis
cutaneous aspergillosis
contaminated intravenous arm boards in patients with neutropenia

at site of catheter insertion

progressive ulcers with thick black eschar
Aspergillosis: lab dx
biopsy of affected tissue ID septate hyphae with acute angle branching

beta-d-glucan detection assay
Zygomycosis: clinical manifestations
caused by Rhizopus, Absidia, and Mucor species

rhinocerebral zygomycosis: most common in diabetics, starts in paranasal sinus and spreads to orbit, hard palate, and brain w/high mortality

pulmonary and cutaneous zygomycoses: immunocompromised, pulmonary lesions/necrotic skin ulcers associated with leukemia, organ transplant, burns
Zygomycosis: epidemiology
transmitted by inhalation of aerosolized spores
Zygomycosis: lab dx
histological examination of tissue ID broad, irregular, non-septate hypahe with wide angle branching, "ribbon-like"
due to molds with hyaline:


may have pre-existing onychomycosis

70% have cutaneous manifestations (cellulitis, target lesions)

may cause sinusitis, rhinocerebral syndrome, endophthalmitis, myositis, and wide dissemination

unlike other fungi, can get (+) blood culture
Fusarium keratitis
soft contact lens wearers needing corneal transplants
Scedosporium infection
Scedosporium apiospermium and Scedosporium prolificans

sinusitis, endophthalmitis, pneumonia, and dissemination, esp to CNS

blood cultures (+) with disseminated disease

histopathology like Aspergillus

(all in all, a lot like Fusarium)
Scedosporium prolificans
resistant to ALL antifungals
Penicillium marneffei
3rd most common infection in Thai AIDS, found in SE Asia and China

fever and numerous umbilicated papular skin lesions, hepatomegaly, adenopathy, pneumonia

dx by ID intracellular yeast with clear central septation
AIDS in Thailand
Penicillium marneffei
Pneumocystis jiroveci
does not have ergosterol

antigenically different between species

primarily alveolar pathogen
Pneumocystis jiroveci: epidemiology
ubiquitous, most humans infected before 4 y.o.

cell-mediated immunity plays role in defense
Pneumocystis jiroveci: clinical manifestations
lethal pneumonia of AIDS patients

fever, nonproductive cough, progressive dyspnea on exertion

most common opportunistic infxn in AIDS patients
Pneumocystic jiroveci pneumonia: lab dx
increased LDH

decreased DLCO, desaturation with exertion
Pythium insidiosum, "water mold"

not a fungus, no chitin, no ergosterol

biflagellate zoospores = infectious form

Thailand -- arterial invasion with arterial insufficiency with thalassemia as risk factor
achlorophyllic algae widely distributed in environment

Prototheca wikerhamii

cutaneous or subQ involvment, often olecranon bursa