Fungi 2

Question 0

Superficial mycoses example: dermatophytosis

Answer 0

Very common
Caused by three different genera of fungi
Infect only superficial keratinization structures, produce keratinases (exotoxins)
Symptoms called Tinea (jock itch, athlete’s foot, ringworm)
Transmitted by fomites or autoinnoculation
Diagnosed by KOH mount, culture
Treat all affected body sites simultaneously with topical antifungal cream, alt oral griseofulvin

Question 1

Superficial mycoses (fungal infections)

Answer 1

Caused by fungal growth on the superficial skin layer

Does not require thermal dimorphism

Very common, but symptoms are minor: itch or discoloration

Treated with topical azoles, alt oral griseofulvin

Question 2

Subcutaneous mycoses

Answer 2

Introduced by trauma exposing subcutaneous tissue to soil or vegetation
Slow spread from trauma site toward trunk by lymphatics
Thermal dimorphism
History of ineffective antibiotic treatment
Treated with oral azoles and in serious cases, amphotericin B and local surgery

Question 3

Subcutaneous mycoses example: sporotrichosis

Answer 3

Caused by sporothrix spp
Thermally dimorphism fungi of vegetation that enters skin through small injuries (thorns, splinters)
Painless ulcer at site spreads up lymphatic over years
If COPD, may be pulmonary; if immunosuppressed, maybe disseminated, meningitis
Diagnose by biopsy and culture at room temperature from pus
Treat normal type with oral azoles, more serious forms with Amphotericin B

Question 4

Systemic mycoses

Answer 4

Environmental: spores/fungi in soil, inhaled into lungs

Thermal dimorphism

Range of severity: asymptomatic clearance to death

Not person to person transmissible

May mimic TB but source is American dirt not foreign crowds

Question 5

Systemic mycoses example: coccidioides

Answer 5

Thermally dimorphic (mold/spherule)
Endemic to US southwest
Mold grows in wet weather, releases infectious arthrospores in dry, spores inhaled, change form
60% mild: asymptomatic or flulike clearance by innate or containment by CM
Moderate: valley fever/desert rheumatism (pulmonary and Erythema nodosum=inflammation of fat cells under skin)
Severe: major pneumonia or dissemination (either bare or in macrophages)
Risk factors: age, race, pregnancy, immunocompromise, occupational high exposure, snow birds
Diagnose by exam, history, PPD, biopsy for spherules, culture, serology for dissemination
Treat if predisposed to complications (oral azoles), meningitis (fluconazole), pregnant or disseminated (Amphotericin B)

Question 6

Opportunistic mycoses

Answer 6

Disease and severity are widely varied depending on patients’ pre-existing conditions
Optimal treatment addresses both infection and underlying problem

Question 7

Opportunistic mycoses example: cyptococcosis

Answer 7

Environmental, enabled by reduced CMI, suppresses host inflammatory response
Presents late in disease with meningitis and skin nodules or pulmonary symptoms
Diagnose with biopsy, CSF, crag (serological test)
Treat with combinations of azoles and Amphotericin B