This site is 100% ad supported. Please add an exception to adblock for this site.

Chapter 20: Fungi


undefined, object
copy deck
What are pseudohyphae?
Long chains of unicellular yeast cells
Molds are aka?
What are dimorphic fungi? Examples?
Growing as spores in the environment, often as yeast in the body. Histoplasma, blastomyces, and coccidioides
Which fungus has a polysaccharide capsule?
Cryptococcus neoformans
What's the classic way of getting sporotrichosis? Manifestations?
Gardener getting a rose thorn prick, with the gradual formation of a subQ nodule. This necroses and ulcerates, spreading along lymphatic tracts up the arm
How is sporotrichosis treated?
Oral potassium iodide or amphotericin B.
What are the three fungi that cause systemic disease in humans? They are endemic to where?
Histoplasma, blastomyces, and coccidioides. Histo and blasto are Mississippi river fungi, wheras coccidioides is found in the southwest.
The disease mechanism of systemic fungal infections is similar to...? Describe in general...?
Similar disease mechanism to TB.
1. Inhalation of spores
2. Local lung infection followed by bloodstream dissemination.
3. In most people, the fungi are then destroyed by cell-mediated immunity.
What are the clinical presentations of the systemic fungal infections?
1. Asymptomatic
2. Pneumonia - chest Xray infiltrates, granulomas with calcifications can follow resolution of the pneumonia.
3. Disseminated disease - meningitis, bone lytic granulomas, skin granulomas/ulcers, and other organ lesions
What's the best way of diagnosing systemic fungal infections?
Tissue biopsy
Treatment for chronic or disseminated fungal disease is usually...?
Itraconazole or amphotericin B
What is the major manifestation of cryptococcus infection? Seen in which population?
Meningoencephalitis (3/4 of cases occur in immunocompromised persons such as AIDS patients)
Why is cryptococcal meningitis fatal without treatment?
Cerebral edema progresses to eventual brainstem compression.
What is the key to cryptococcus diagnosis?
Lumbar puncture and analyzing the CSF. Also make sure to measure opening pressure.
What is the usual treatment of an AIDS patient with cryptococus infection?
Amphotericin B and flucytosine
Describe where Candida can be seen in normal immunocompetent hosts?
1. Oral thrush
2. Vaginitis
3. Diaper rash
What are the risk factors for developing vaginitis?
Women taking antibiotics, oral contraceptives, or during menses and pregnancy
What are the more serious manifestations of Candida in immunosuppressed patients? What should be examined in these patients?
1. Esophagitis
2. Disseminated - Can invade virtually every organ
Examine retina for cotton spots, check blood cultures.
What is an aspergilloma?
An aspergillus fungal ball in the lung cavitations from TB or malignancies.
What mycotoxin is produced by Aspergillus? What does it do?
Aflatoxin - causes liver damage and liver cancer.
What disease does Actinomyces cause? What is an important microscopic feature of Actinomyces?
Eroding abscesses following trauma to the mucous membranes of the mouth or GI tract.
Sulfur granules.
Describe Nocardia microscopically? Frequently misdiagnosed as?
Partially acid-fast beaded branching thin filaments. Frequently misdiagnosed as TB.
Describe treatment for Actinomyces and Nocardia?
Treatment is a SNAP!
Sulfa for Nocardia, Actinomyces give Penicillin.
Describe the adverse effects (and ways to mitigate them) of Amphotericin B?
1. Renal toxicity (administer with normal saline)
2. Acute febrile reaction (give aspirin)
3. Anemia
4. Phlebitis of the vein at the IV site

Deck Info