Fungal Infections

Question 1

1. Name the dimorphic fungi that cause human disease in North America.

Answer 1

Histoplasmosis, Blastomycosis, Coccidiodis, Sporothrixis

Question 2

2. Determine which groups of patients are more susceptible to systemic fungal infections.

Answer 2

immunocompromised, esp. those with impaired cell-mediated immunity (HIV), malignancy and cancer treatment, elderly, those with significant exposure; hospital stay/ surgery

Question 3

3. Describe why antibacterials are not effective against fungi.

Answer 3

antibiotics target cell wall and protein synthesis targets that are not present in eukaryotic fungal cells

Question 4

1. Explain how the clinical microbiology lab aids the physician in making a diagnosis in each of the presented cases (what lab tests should be ordered and the results consistent with each diagnosis). blasto, candida, aspergillus, crypto, tinea

Answer 4

Blasto: KOH in water looking for broad based yeast (culture also, not antibodies)
Candida: culture looking for germ tubules and yeast
Aspergillus: clinical features: fluffy pulmonary infiltrates, halo sign
Crypto: antigen test for polysaccharide coat (also smear, culture; no antibody)
Tinea: scrapping on KOH (culture also)

Question 5

2. Discuss the target organs for each of the presented fungi. blasto, candida, aspergillus, crypto, tinea

Answer 5

Blasto: lungs and skin, bone, UG and brain
Candida: skin, mucous barriers, GI tract
Aspergillus: skin, lungs, blood, CNS, sinuses, allergic rxn. and fungus ball
Crypto: lungs, skin, prostate, blood stream, CNS
Tinea: skin