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Week 1 - Day 4 notes contd Fungus


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Name the fungus infections on the superficial layer of skin? Appearence?
1. Pityriasis versicolor- Malassezia furfur, multicolored (hypo or hyperpigmented)
2. Tinea nigra - Exophilala werneckii, black
The common dermatophytes? What fungal infections do they cause?
1.Microsporum, trichophyton, dermatophyton
2. Tinea corpris,T.capitis, T.Crusis (jock itch), T. pedis (athlete's foot)
Superficial fungal infection caused by Exophialla werneckii. Now called Phaeoannellomyces werneckii
Tinea nigra (not a true tinea)
Pityriasis versicolor is also superficial and is caused by what organism?
Malassezia furfur
M. furfur appears in what pattern on KOH?
spaghetti & meatballs
Fluoresces bright green on wood's light (a dermatophyte) and is carried by animals.
Copper-colored soil saprophytes cause this condition. Phialophora and Cladosporium
Hint: THe chromo man blasting mushrooms on skin
Tx for sporotrichosis
Oral KI or amphotericin B (if systemic)
First line drugs for dermatophytoses
topical imidazoles
Used to treat tinea capits and tinea unguinum. Given orally
Primary manifestation of Cryptococcus? Describe this fungal bug?
What population of patients are susceptible to Cryptococcus infections?
1. meningoencephalitis
2. Polysaccharide encapsulated yeast (not dimorphic)
3. AIDS patients
Stain to see capsules of cryptococcus
india ink
Treatment of cryptococcus (2 drugs)
ampho B and flucytosine
IF you suspect disseminated candidiasis, what part of the body must be checked for fluffy white candidal patches?
retina with ophthalmoscope
Two fungi like bacteria
Nocardia/ actinomycetes
Treatment for nocardia
Two antifungals given for more serious infections (one is orally administered. the other is not)
ampho B (not oral. IV or intrathecal). & Itraconazole (oral)
In addition to the azoles, ----- and ----- may be given for superficial fungal infections
griseofulvin and nystatin
T/F the azotemia caused by AmphoB is not reversible and will not subside when the drug is stopped.
False. It is reversible!
A common side effect after infusion of amphoB
acute febrile reaction
name two other side effects of ampho B
anemia, phlebitis at IV site
How does ampho B cause lysis of the fungal cell?
binds to ergosterol and disrupts membrane
Why is flucytosine rarely used alone?
rapid development of resistance
Flucytosine use is largely restricted to Tx of ---- ---- in conjunction with amphoB
crypto meningitis
Side effects of Flucytosine
bone marrow suppression, nausea, diarrhea (like any other antimetabolite)
Tx for chronic mucocutaneous candidiasis
Why is there gynecomastia, and decreased sex drive on ketoconazole?
P450 inhibition causes inhibition of testosterone synthesis
Ketoconazole side effects other than inhibition of testosterone synthesis:
hepatotoxicity, adrenal suppression, GI upset common
The big picture of fluconazole is that it kills what organism very well? Think yeast infections. Only one dose of fluconazole is needed to Tx yeast infections.
Candida albicans
The azoles work by inhibiting ----- ------ which is necessary for ergosterol synthesis.
P450 system
Tx of oral, esophageal, and GI candidiasis. Not absorbed orally
Nystatin, swish and swallow
Like amphoB, nystatin binds to -----.
Griseofulvin is used to treat dermatophyte infections by what mechanism?
prevents mitosis by preventing spindle formation
KI is used to treat what fungal infection if it is not systemic?
Drug that blocks fungal ergosterol synthesis by inhibiting formation of squalene epoxide from squalene.
Where does terbinafine accumulate?
What the function of KOH -in the preparation of fungal specimen?
To digest any non-fungal debri
Name the essential sterol for fungal cell membrane?
Name drugs that bind to it?
Name drugs that inhibit this sterol's synthesis?
1. Ergosterol
2. Amphotericin B and Nystatin
(they punch holes in the cell membrane)
3. Ketoconazole (inhibits the synthesis of ergosterol)
Who are susceptible to Sporothrix Schenckii?
(hint for both: Pot)
Location of infection and presentation?
2.Potassium iodide
3.Due to trauma - gets to lymphatics
Track of nodules along the subQ lymp - that necrosis and propagate.
1.Route of infection of Cryptococcus neoformans (not this is not coccidiodes)
2. Describe the presentation of the Cryptococcal meningitis?
1. Pigeon droppings
2. Subacute to chronic meningitis. notably Cerebral edema--> brainstem compression.
3. Amphotericin B and Flucytosine
Histoplasma capsulatum and Blastomyces dermatitidis are common in what region of the US? Coccidiodes immitis?
What kind of fungus are they?
Common clinical presentation?
1. Histoplasma capsulatum (not capulated) and Blastomyces are endemic in regions around the Mississippi river.
2. Coccidiodes immitis - Southwestern
3. All present like TB (inhaled,mild-chronic infections, granulomas,can disseminate in blood, Skin like PPD)
Histoplasma capsulatum, Blastomyces dermatitidis, Coccidiodes immitis
How do they differ from TB?
1.No person to person transmission
2.Fungi are spores, not acid-fast bacteria
Clinical presentation of Candida Albicans in Normal host? Immunocomprimised?
1. Diaper rash- warm moist areas (skin folds too in adults)
2. Vaginitis - thick copious secretion
3. Oral thrush-difficult to scrape

B.Disseminated - use Ampho B or oral imidazole= Fluconazole
Asthmas is associated with this fungus?
1.Aspergillus flavus
2.Aspergillus flavus stimulates IgE type I hypersensitivity reaction.
Where are Aspergilloma usually formed in the lungs?
Name the Hypersensitivity rxn Aspergillus can cause?
1.In cavities - made by TB or cancer
2. Aspergillomas
3. Type I and Type IV(cell mediated)
Name two fungi like bacteria? what type of bacteria are they and describe them?
1. Actinomycetes and Nocardia (both g+)
A. Actinomycetes- g+ anaerobic,normal flora,forms sulphur like granules (these are colonies not sulphur), can form abscesses in mouth.
Tx= penicillin
B. Norcardia-g+,aerobic, not nl flora, Acid-fast, lung abscess,
Tx: Sulpha (TMP-SMX)

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