Fungus & Yeast Infections

Question 1

Candidiasis:

Answer 1

1. Yeast-like fungi form true hyphae & pseudohyphae
2. Human and animal reservoirs, detected in normal fecal flora
3. Host defenses allow access to bloodstream through colonized skin or mucosa absorption via GI wall
4. > 90% w/ HIV develop oropharyngeal candidiasis
5. C albicans is the MCly identified etiology (C dubliniensis in pts w/ HIV)
6. Candida endophthalimitis: classic lesions are lrg, off-white, “cotton ball”, indistinct boarders
7. Workup:
   • KOH smear, gram stain, methylene blue for fungal cells
   • Species ID w/ FISH test
8. Tx: azole antifungals, glucan synthesis inhibitors, polyenes, allyamines

Question 2

Cutaneous Candidiasis:

Answer 2

1. Unusual, diffuse eruption over trunk, thorax, & extremities (pruritis, vesicles in anal region, folds, axilla, hands and feet)
2. Intertrigo: vesciculopustules enlarge & rupture in intertriginous areas cause maceration & fissuring (scalloped boarder w/ white rim of necrotic epidermis

Question 3

GI Tract Candidiasis:

Answer 3

1. Oropharyngeal Candidiasis (OPC) – asymp. Or sore/painful mouth, burning mouth/tongue, dysphagia, white thick patches on oral mucosa
   o 5 Types: membranous (MC), erythematis, chronic atrophic, angular cheilitis, mixed

Question 4

Respiratory Tract Candidiasis:

Answer 4

1. > 25% hospitalized pts w/ Candida species

Question 5

GU Tract Candidiasis:

Answer 5

1. Vulvovaginal Candidiasis (VVC): 2nd MC cause of vaginitis. Red
2. Candida Balanitis: penile prurutis w/ whitish patches on penis, acquired thru sexual contact
3. Fungal Balls: accumulation of fungal material in renal pelvis, intermittent UT obstruction w/ renal insufficiency

Question 6

Cryptococcosis:

Answer 6

1. Caused by an inhalation of encapsulated yeast spore in pulmonary alveoli
2. Crucial factor = immune status of the host
3. Characteristic lesion: cystic cluster of yeast, causes asymptomatic pulm infection followed by meningitis
4. Pulmonary cryptococcosis: variable, slowly progressive →SVC syndrome
5. CNS Cryptococcosis: meningitis/meningoencephalitis MC manifestations. Fatal w/o appropriate therapy
6. Workup bx and fungal stains/cultures of cutaneous lesions, blood & CSF culture, cryptococcal Ag testing
7. Tx:
   • Cryptococcal meningitis w/ AIDS: amphotericin B x2 wks followed by fluconazole for 8-10 wks minimum
   • Crytopcoccal meningitis w/o AIDS: same as above

Question 7

Dermatophyte:

Answer 7

1. Group of fungi (ringworm) that invade the dead keratin of skin, hairs, and nails
2. Dematophytosis: superficial fungal infection caused by dermatophytes
3. Tinea capitis = scalp, Tinea cruris = groin, Tinear barbae = beard face area & neck, Tinea Unguium = nail
4. 2 wks from inoculation, visible skin changes. Pruritis = main symp
5. Pts w/ tinea capitis experience hair loss
6. Workup: microscopic exam of skin scrapping, nail specimen, plucked hairs; treated w/ KOH. Fungal cultures
7. Wood Light (UV light) exam to dx tinea capitis
8. Tx:
   • Tinea Corporsis: topical agents or w/ oral antifungals in severe
   • Tinea Corporis & Nail Infections: topical therapy ineffective! Oral antimycotic drugs, requires baseline LFTs
   • Med classes = azoles & allylamines

Question 8

Histoplasmosis:

Answer 8

1. Caused by dimorphic fungus that remains in a mycelia form at ambient temps
2. MC Endemic fungal infection→found in Ohio, Missouri, & Mississippi River valleys
3. Clinical dz usually in immunocompromised or exposed to high inoculums
4. Acute pulm histoplasmosis = 90% asymp
5. Progressive disseminated histoplasmosis risk factors: exposure as an infant, AIDS w/ CD4 4 wks – itraconazole 6-12 wks
6. Chronic Pul: often fatal if not txed, itracoazole x 1 yr or sx

Question 9

Pneumocytis Carinii:

Answer 9

1. Pneumocystis carinii pneumonia is MC opportunistic infection in HIV pts
2. Multiple host immune defects allow for uncontrolled replication and develop dz
3. Symptoms are nonspecific, may present in any organ system. In HIV, subacute indolent course and presents later.
4. Workup: sputum, lactic dehydrogenase (will incr), PCR (distinguish latent vs active), B-D-Glucan, CXR
5. Tx:
   • May initiate before workup is complete in high risk pts
   • Pts w/o HIV respond to tx in 4-5 days, w/ HIV in 8 days
   • Trimethoprim-sulfamethoxazole, corticosteroids
   • Prevent: smoking cessation, chemoprophylaxis in HIV pts (d/c in pts whose CD >200 for 3 consecutive months)