Semester 2 - Fungal Infections Flashcards Preview

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Flashcards in Semester 2 - Fungal Infections Deck (38)

What are some characteristics of fungi?

Eukaryotic, multicellular or unicellular
Includes yeasts and moulds
Cell wall includes chitin (important PAMP and antifungal target)
Complex life cycles


How are fungal infections classified?

By location
Superficial, skin - tinea
Subcutaneous - sporothrichosis
Systemic - blastomycosis, histomycosis
Opportunistic - Candidiasis


What are some general characteristics of fungi?

Heterotrophic - parasitic or symbiotic relationships with other organisms, feed off organic matter
Eukaryotic, aerobic, indeterminate growth, heterogenous and ubiquitous, chitin containing cell wall
Decompose organic matter


What are the body forms that fungi can have?

unicellular, filamentous, mycelium, sclerotium, multicellular


What are the functions of spores?

may be a product of both sexual and asexual reproduction
allows organism to move to new sources of food
allows genetic diveristy
allows resistance from harsh environmental conditions


What are some characteristics of yeast? And some human pathogens?

unicellular fungi, or unicellular stage of dimorphic fungi
many reproduce by budding
sexual and asexual stages
Malessezia sp.
Candida albicans
Cryptococcus neoformans


What are cutaneous or superficial mycoses?

Fungal infection of the outermost layer of skin, hair, nails
Generally do not interact with host organism
Inflammation occurs when infection breaches superficial layer - may lead to host cell mediated immune response and clearing of infection


How are superficial/cutaneous fungal infections transmitted?

Contact with infected persons, animals, soil


What is tinea versicolor?

Blotchy hyper/hypopigmentation of the skin, does not darken in the sun
itchy, scaley
KOH prep of scraped skin reveals spaghetti and meatballs appearance of hyphae and spores
Malessezia sp.


What is Tinea pedis?

Fungal infection of the foot
Trichophyton sp.


What is Tinea nigra?

Brown/black macules typically on palms
Non inflammatory non scaling non itching
Associated with contaminated soil, wood, compost
Hortaea werneckii


What is tinea capitis?

Fungal infection of the head and scalp
patches of hairloss, inflammation, scaling, itching, dandruff
Trichophytum and microsporum sp. most common


What is pityriasis captitis?

Seborrheic dermatitis (inflammation and scaling)
Dandruff (flaking of skin from scalp)
Malessezia sp.


What does a late stage chromoblastomycosis infection look like?

whole limb involvement, cauliflower appearance
risk of ulceration, secondary infection


How is chromoblastomycosis diagnosed?

KOH staining of lesion scraping


Where do systemic mycoses infect?

Pass through the bloodstream
Primary systemic mycoses generally originate in the lung, and undergo hematogenous spread to other organs - transmission by respiratory droplets


What causes systemic mycoses infections?

Dimorphic fungal pathogens - assume different morphologies at different body temperatures
Mycelial at room temp
Yeast like/spore like at body temp
Human pathogens - blastomyces dermatiditis, histoplasma capsulatum, coccidoiodes immitis, paracoccidiodes brasiliensis


What does a blastomyces dermatiditis infection look like?

Fungus lives in soil and decaying matter, endemic in North America
Inhalation of spres disturbed from soil, forest etc
50% exposed are asymptomatic
Pulmonary blastomycosis (most common) - fever chills myalgia arthralgia
Cutaneous blastomycosis
Osteoaricular blastomycosis - hematogenous spread to bone and joints
Genitourinary blastomycosis - hematogenous spread to genito urinary tract leads to prostatitis, epididymitis, testitis etc


How is a blastomyces dermatidits infection diagnosed?

Sample from infected area (sputum, skin, biopsy)


How is histoplasma capsulatum transmitted?

Inhalation of airborne spores from materials contaminated with bodily fluids (feces, urine)
Animal dropping, caves, demolition projects, soil


What does a histoplasma capsulatum infection look like?

95% patients asymptomatic, symptoms resemble TB in syptomatic individuals
Acute - pulmonary, fever chills, cough, chest pain
Chronic pulmonary - chest pain, SOB, fever, sweating, coughing up blood
Disseminated histoplasmosis - multiorgan invovlement associated with skin lesions rapidly fatal


What is tinea cruris?

Jock itch
Often a spread of athletes foot


How is a superficial/cutaneous mycoses infection diagnosed?

Symptoms and presentation
KOH stain of scrapings


What is a subcutaneous mycoses?

Chronic, localized infection of the skin and tissue
May affect lymphatic system, invade extra-dermal tissues


What is Candida albicans

Thrush, yeast infectinon
Commensal organism of the skin


What is oral candidiasis?

Aka thrush
Associated with immunosuppressed patients
White patches, plaques on the tongue, difficulty swallowing


What is vulvo-vaginal candidiasis

Yeast infection
Pruritis, thick discharge, dyruria


What are other forms of Candida albicans?

Esophageal, urinary tract, penile (candida calantidis), Gastrointestinal, renal, systemic, disseminated


How is Candida albicans diagnosed?

Symptoms, analysis of scraping (false positives)


How is Candida albicans transmitted?

Occurs (contact, mucosal), but more often an outgrowth of commensal yeast
Not an STI but associated with sexual activity. Can be acquired but for the most part commensal (Similar to UTIs, not an STI but associated with sexual activity)


What is pneumocystis jiroveci?

Formally P. carinii
Pneumocystosis, PCP pneumonia, fungal pneumonia
Commensal organism of the lung


What does a pneumocystis jiroveci infection look like?

Fever, chills, non-productive cough, difficulty breathing, tachypnea, tachycardia
Extra-pulmonary complications: CNS, bone marrow, eyes, GI (rare)


How is pneumocystis jiroveci diagnosed?

Elevated serum lactate dehydrogenase (LDH) associated with PCP pneumonia associated with cell damage/tissue breakdown. (non-specific indicator)


What is sporotrichosis?

Sporothrix schenchii infection of the cutaneous/subcutaneous layers and adjacent lymphatic system
Aka rose gardener's disease
Cutaneous: painless ulcer on the skin that progresses to a fluid filled blister
Lymphocutaneous: secondary lesions along lymphatic channels
Complications: (rare) pulmonary (pneumonia), CNS (meningitis) bone (arthritis)


How is sporotrichosis transmitted and diagnosed?

contaminated soil
diagnosed with biopsy


What is chromoblastomycosis?

F. pedrosi, P. verrecosa, C. carrionii, F. compacta
Aka verrecous dermatitis
Woldwide distribution, most prevalent in tropical, subtropical areas, associated with agricultural workers


What does a chromoblastomycosis infection look like?

Chronic subcutaneous infection - symptoms arise years following inoculation
Warty nodules typically on lower extremities, plaques crust over, leaving ivory coloured scars over and around nodules. May spread cutaneously or to adjacent lymphatics.


How is a histoplasma capsulatum infection diagnosed?

Sample from infected area (sputum, skin, biopsy)