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36 Cards in this Set

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Fungi are eucaryotic cells, which lack chlorophyll, so they cannot generate energy through photosynthesis. TRUE/FALSE
TRUE.
List 6 varieties of fungi.
1. yeast
2. hyphae
3. molds
4. spores
5. dimorphic fungi
6. saprophytes
What are dimorphic fungi?
Fungi that can grow as either a yeast or mold.
What is ergosterol?
ergosterol is the essential sterol in fungi, while cholesterol is the essential sterol in fungi. The antibiotics amphoteracin B and nystatin bind to ergosterol and punch holes in the fungal cell membrane. Ketoconazole inhibits ergosterol synthesis.
Fungal cell walls are potent antigens to the human immune system. TRUE/FALSE
TRUE.
What is the fungal capsule?
This is a polysaccharide coating that surrounds the cell wall. This antiphagocytic virulence factor is employed by Cryptococcus neoformans. It is visualized by India ink stain.
List 2 superficial fungal infections.
1. Pityriasis versicolor
2. Tinea nigra

Pityriasis imparts hypo/hyperpigmented skin spots. It is caused by Malassezia furfur.
Tinea nigra, causes black painless patches on the soles of the hands and feet. It is caused by Exophiala wernickii.
How are these diseases diagnosed?
It is based on microscopic exam of skin scrapings, mixed on a slide with KOH. The KOH digests nonfungal debris.
How are these treated?
Treatment consists of spreading dandruf shampoo containing selenium sulfide over the skin. Topical antifungal imidazoles can also be used.
What are the Dermatophytoses?
They are a category of cutaneous fungal infections caused by more than 30 species of fungi. They live in the dead, horny layer of the skin, hair and nails.
List three common dermatophytes.
1. microsporum
2. trichophyton
3. epidermophyton
List 5 types of Tinea.
1. Tinea corporis
2. T. cruris(jock itch)
3. T. pedis
4. T. capitis
5. T. unguium
Direct examination of hair and skin with Wood's lamp(UV light at a wavelength of 365nm). Certain species will fluoresce a brilliant green. TRUE/FALSE
TRUE
The first line drugs for treatment of dermatophytoses are the topical imidazoles. TRUE/FALSE
TRUE. Oral Griseofulvin may be used for T. unguium and capitis.
List 2 major subcutaneous fungal infections.
1. Sporothrix schenckii(sporotrichosis)
2. Phialophora
3. Cladosporium
What is Sporotrichosis/
It is an occupational hazard for gardeners. Following a prick with a thorn contaminated with Sporothrix schenckii. The subcutaneous nodule becomes necrotic and ulcerates. Lymphatic tracts up the arm are affected as well.
How is Sporotrichosis treated?
It is treated with oral potassium or Amphoteracin B.
What is Chromoblastomycocis?
It is a subcutaneous infection caused by a variety of copper colored soil saprophytes(Phialophora/Cladosporium) It is found on rotting wood. Violet colored warts may appear from weeks to years later. It is treated with Itraconazole and local excision.
List three systemic fungal infections.
1. Histoplasma capsulatum
2. Blastomyces dermatitidis
3. Coccidioides immitis

All 3 are dimorphic, and grow on Sabourauds agar at 25 degrees C.
Coccidioides is endemic to the southwestern US. TRUE/FALSE
TRUE. Coccidioides has become the 2nd most common opportunistic infection in AIDS patients.
Do these three infections have a similar mechanism of disease?
Yes. They are acquired by inhalation, and they are inhaled as a spore form and never transmitted from person to person. Spores come from soil, bird droppings or vegetation. It can disseminate in the bloodstream.
In most persons the fungi are destroyed by the cell mediated immune system. Antigenic preparations called coccidioidin and histoplasmin are like the PPD of M. tuberculosis. TRUE/FALSE
TRUE.
Histoplasma/Blastomyces/Coccidiooides, have 3 clinical presentations. What are they?
1. Asympptomatic(majority of cases are of this classification).
2. Pneumonia
3. Disseminated (rare, may cause meningitis, and bone lytic granulomas, and skin granulomas, that break down into ulcers.
How are these diagnosed?
Biopsy of tissue, bronchoscopic biopsy, and tissue is examined with silver stain.
What is their treatment?
Acute pulmonary histoplasmosis and coccidiooimycosis usually require no treatment, as the infection is mild.
For disseminated disease, Itraconazole or Amphoteracin B is required for months.
What is Cryptococcus neofromans?
It is a polysaccharide encapsulated yeast(not dimorphic). Its major manisfestation is meningoencephalitis. It is found in nature, especially in pigeon droppings. yeast spread via blood to the brain.
It is fatal without treatment.
What is the treatment?
Amphoteracin B and Flucytosine. Treatment may last for 6 months.
AIDS patients may require lifelong therapy.
List three conditions caused by Candida albicans.
1. Oral thrush
2. Vaginitis
3. Diaper rash
Candida can invade the bloodstream and virtually every organ. TRUE/FALSE
TRUE. When systemic Candidiasis is suspected, the retina must be examined with the opthalmoscope.
Candida is normal flora, and often cultured from urine, sputum, and stool. It should never be isolated from the blood. TRUE/ FALSE
TRUE.
What is Aspergillus flavus?
The spores of A. flavus float in the air everywhere. Some persons develop asthma like symptoms to these spores. Systemic corticosteroids are an effective treatment.
Persons with lung cavitations from tbc or malignancies can grow an aspergillus fungal ball in the cavity, called an aspergilloma. TRUE/FALSE
TRUE. A flavus and other fungi produce toxins that cause liver damage and liver cancer.(mycotoxins). That produced by A. flavus is called aflatoxin. It may contaminate peanuts, grains and rice.
What are actinomycetes?
They are bacteria acting like fungi. They are procaryotic orgasnisms. They grow as mycelia inwater and soil.
What is Actinomycetes Israeelii?
1. It is a Gram + beaded filamentous anaerobic organism that grows as normal flora in the mouth and GI tract.
2. It may cause eroding abscesses(cervicofacial, abdominal and thoracic)
3. When examined under the microscope, the pus has yellow granules, called sulfur granules, though they are not really composwed of sulfur.
4. Treatment is with penicillin G and surgical drainage.
What is Nocardia asteroides?
It forms weakly Gram +, partially acid fast branching thin filaments. It is not considered normal flora.
It is often misdiagnosed as tbc. It is inhaled.
What is the treatment of Nocardia?
Trimethoprim/Sulfamethoxazole.