Semester 2 - Fungal Infections

Question 0

How are fungal infections classified?

Answer 0

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

Question 1

What are some characteristics of fungi?

Answer 1

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

Question 2

What are some general characteristics of fungi?

Answer 2

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

Question 3

What are the body forms that fungi can have?

Answer 3

unicellular, filamentous, mycelium, sclerotium, multicellular

Question 4

What are the functions of spores?

Answer 4

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

Question 5

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

Answer 5

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

Question 6

What are cutaneous or superficial mycoses?

Answer 6

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

Question 7

How are superficial/cutaneous fungal infections transmitted?

Answer 7

Contact with infected persons, animals, soil

Question 8

What is tinea versicolor?

Answer 8

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.

Question 9

What is Tinea pedis?

Answer 9

Fungal infection of the foot

Trichophyton sp.

Question 10

What is Tinea nigra?

Answer 10

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

Question 11

What is tinea capitis?

Answer 11

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

Question 12

What is pityriasis captitis?

Answer 12

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

Question 13

What does a late stage chromoblastomycosis infection look like?

Answer 13

whole limb involvement, cauliflower appearance

risk of ulceration, secondary infection

Question 14

How is chromoblastomycosis diagnosed?

Answer 14

KOH staining of lesion scraping

Question 15

Where do systemic mycoses infect?

Answer 15

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

Question 16

What causes systemic mycoses infections?

Answer 16

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

Question 17

What does a blastomyces dermatiditis infection look like?

Answer 17

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

Question 18

How is a blastomyces dermatidits infection diagnosed?

Answer 18

Sample from infected area (sputum, skin, biopsy)

Question 19

How is histoplasma capsulatum transmitted?

Answer 19

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

Question 20

What does a histoplasma capsulatum infection look like?

Answer 20

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

Question 21

What is tinea cruris?

Answer 21

Jock itch

Often a spread of athletes foot

Question 22

How is a superficial/cutaneous mycoses infection diagnosed?

Answer 22

Symptoms and presentation

KOH stain of scrapings

Question 23

What is a subcutaneous mycoses?

Answer 23

Chronic, localized infection of the skin and tissue

May affect lymphatic system, invade extra-dermal tissues

Question 24

What is Candida albicans

Answer 24

Thrush, yeast infectinon

Commensal organism of the skin

Question 25

What is oral candidiasis?

Answer 25

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

Question 26

What is vulvo-vaginal candidiasis

Answer 26

Yeast infection

Pruritis, thick discharge, dyruria

Question 27

What are other forms of Candida albicans?

Answer 27

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

Question 28

How is Candida albicans diagnosed?

Answer 28

Symptoms, analysis of scraping (false positives)

Question 29

How is Candida albicans transmitted?

Answer 29

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)

Question 30

What is pneumocystis jiroveci?

Answer 30

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

Question 31

What does a pneumocystis jiroveci infection look like?

Answer 31

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

Question 32

How is pneumocystis jiroveci diagnosed?

Answer 32

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

Question 33

What is sporotrichosis?

Answer 33

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)

Question 34

How is sporotrichosis transmitted and diagnosed?

Answer 34

contaminated soil

diagnosed with biopsy

Question 35

What is chromoblastomycosis?

Answer 35

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

Question 36

What does a chromoblastomycosis infection look like?

Answer 36

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.

Question 37

How is a histoplasma capsulatum infection diagnosed?

Answer 37

Sample from infected area (sputum, skin, biopsy)