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48 Cards in this Set
- Front
- Back
What are the common characteristics of Systemic Mycoses? |
- All can cause pneumonia and disseminate
- All caused by dimorphic fungi - cold (20°C) = mold; heat (37°C) = yeast (exception: cocci is a spherule not yeast in tissue) - Treat local infection with fluconazole or itraconazole - Treat systemic infection with amphotericin B - Systemic mycoses can mimic TB (granuloma formation) but there is no person-to-person transmission |
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How do Systemic Mycoses compare to TB?
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- Both have granuloma formation
- Mycoses do not have person-to-person transmission |
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What are the systemic mycoses?
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- Histoplasmosis
- Blastomycosis - Coccidioidomycosis - Paracoccidioidomycosis |
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Which mycoses is endemic to the Mississippi and Ohio River valleys? What does it cause? Pathologic features?
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Histoplasmosis
- Causes pneumonia - Macrophages filled with histoplasma (smaller than RBCs) - "Histo Hides (within macrophages)" - Associated with bird and bat droppings |
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Which mycoses is endemic to the states east of the Mississippi River and Central America? What does it cause? Pathologic features?
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Blastomycosis
- Causes inflammatory lung disease and can disseminate to skin and bone - Forms granulomatous nodules - Blasto Buds Broadly (same size as RBCs) |
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Which mycoses is endemic to the SW US and California? What does it cause? Pathologic features?
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Coccidioidomycosis
- Causes pneumonia and meningitis - Can disseminate to skin ("desert bumps" = erythema nodosum) and bone ("desert rheumatism" = arthrlagias) - Case rate increases after earthquakes (spores in dust are thrown up in the air and become spherules in lungs) - Spherule (much larger than RBCs) filled with endospores - "Coccidio Crowds" |
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Which mycoses is endemic to Latin America? What does it cause? Pathologic features?
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Paracoccidioidomycosis
- Budding yeast with "Captain's Wheel" formation (much larger than RBCs - "Paracoccidio parasails with the captain's wheel all the way to Latin America" |
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What is the relative size of the systemic mycoses to RBCs?
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- Histoplasmosis: smaller than RBC
- Blastomycosis: same size as RBC - Coccidioidomycosis: much larger than RBC - Paracoccidioidomycosis: much larger than RBC |
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What is the location in which the systemic mycoses are endemic?
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- Histoplasmosis: Mississippi and Ohio River valleys
- Blastomycosis: states east of Mississippi River and Central America - Coccidioidomycosis: SW US, California - Paracoccidioidomycosis: Latin America |
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What are the cutaneous mycoses?
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- Tinea versicolor
- Other Tinea: pedis (foot), cruris (groin), corporis (ringworm on body), capitis (head/scalp), unguium (onychomycosis - on fingernails) |
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What is the cause of Tinea Versicolor? When is it more common?
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Malassezia Furfur - "spaghetti and meatball" appearance
- More common in hot, humid weather |
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What does Malassezia Furfur cause?
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- Degradation of lipids produces acids that damage melanocytes
- Causes hypopigmented and/or hyperpigmented patches - Causes Tinea Versicolor |
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How do you treat Tinea Versicolor (Malassezia Furfur)?
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Topical miconazole, selenium sulfide (Selsun)
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What causes the other Tineae (eg, pedis, cruris, corporis, capitis, unguium)? Types of lesions?
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- Caused by Dermatophytes (Microsporum, Trichophyton, and Epidermophyton)
- Pruritic lesions with central clearing that resembles a ring |
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What are the Dermatophytes that cause Tineae? Appearance?
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- Microsporum
- Trichophyton - Epidermophyton See mold hyphae in KOH prep but not dimorphic |
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What are the opportunistic fungal infections?
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- Candida albicans
- Aspergillus fumigatus - Cryptococcus neoformans - Mucor and Rhizopus species - Pneumocystis jirovecii - Sporothrix schenckii |
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Which fungus causes oral and esophageal thrush in immunocompromised (neonates, steroids, diabetes, AIDS), vulvovaginitis (diabetes, use of antibiotics), diaper rash, endocarditis in IV drug users, disseminated infection (to any organ), and chronic mucocutaneous infection?
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Candida albicans (alba = white)
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What forms does Candida albicans have?
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Dimorphic yeast
- Pseudohyphae and budding yeasts at 20°C - Germ tubes at 37°C |
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What kind of Candida albicans infection occurs in patients who are immunocompromised (neonates, steroids, diabetes, AIDS)? Treatment?
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Oral and esophageal thrush - treat with fluconazole or caspofungin
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What kind of Candida albicans infection occurs in patients who have diabetes or are using antibiotics? Treatment?
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Vulvovaginitis - treat with topical azole
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What kind of Candida albicans infection occurs in infants?
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Diaper rash
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What kind of Candida albicans infection occurs in patients who are IV drug users?
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Endocarditis
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How do you treat systemic Candida albicans infections?
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Fluconazole, Amphotericin B, OR Caspofungin
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Which fungus can cause invasive infection, allergic bronchopulmonary infection, and masses of fungus in lung cavities?
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Aspergillus fumigatus
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Characteristics of Aspergillus fumigatus? Appearance?
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- Septate hyphae branch at 45° angle ("think A for Acute Angles in Aspergillus")
- Not dimorphic - Conidiophore with radiating chains of spores |
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Who is most likely to get invasive Aspergillus fumigatus infection?
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Immunocompromised and those with chronic granulomatous disease
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Which form of Aspergillus fumigatus infection is associated with asthma and cystic fibrosis? What can it cause?
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Allergic Bronchopulmonary Aspergillosis (ABPA)
- May cause bronchiectasis and eosinophilia |
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What form of Aspergillus fumigatus infection is more common after TB infection?
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Aspergillomas in lung cavities
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What can some species of Aspergillus fumigatus produce? Implications?
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Some species produce AFLATOXINS which are associated with Hepatocellular Carcinoma
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Which fungus is found in soil and pigeon droppings and can cause meningitis?
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Cryptococcus neoformans
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Characteristics of Cryptococcus neoformans?
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- Heavily encapsulated yeast with unequal budding
- Not dimorphic - Culture on Sabouraud agar - Stains with India ink (picture) and mucicarmine - Latex agglutination test detects polysaccharide capsular antigen and is more specific |
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What disease is caused by Cryptococcus neoformans infection? How is it acquired?
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- Cryptococcal meningitis
- Cryptococcosis - Acquired through inhalation of fungus found in soil and pigeon droppings - Hematogenous dissemination to meninges |
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Which fungus causes "soap bubble" lesions in the brain?
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Cryptococcus neoformans
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Which fungus causes disease mainly in ketoacidotic diabetic and leukemic patients?
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Mucor and Rhizopus species → Mucormycosis
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What is the pathogenesis of Mucor and Rhizopus species?
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- Fungi proliferate in blood vessel walls when there is excess ketone and glucose
- Penetrates cribiform plate - Enters brain → rhinocerebral and frontal lobe abscesses |
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What are the symptoms of infection by Mucor and Rhizopus species?
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- Headache
- Facial pain - Black necrotic eschar on face - May have cranial nerve involvement (due to abscesses in rhinocerebral, frontal lobes) |
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How do you treat Mucor and Rhizopus species infections?
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Amphotericin B
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What is the appearance of Mucor species?
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Irregular, broad, non-septate hyphae branching at wide angles
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Which fungus is usually asymptomatic but in immunosuppressed (eg, AIDS) causes a diffuse interstitial pneumonia?
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Pneumocystis jirovecii
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Who is affected by Pneumocystis jirovecii infection? How?
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- Inhaled
- Most infections are asymptomatic - Infection in immunosuppressed patients (eg, AIDS) predisposes to disease → Pneumocystis pneumonia (PCP) - PCP is a diffuse interstitial pneumonia |
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What are the characteristics of Pneumocystis pneumonia (PCP)? Diagnosis?
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- Diffuse interstitial pneumonia
- Diffuse, bilateral CXR appearance - Diagnosed by lung biopsy or lavage - Disc-shaped yeast forms on methenamine silver stain of lung tissue |
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What is the appearance of Pneumocystis jirovecii?
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Yeast:
- Disc-shaped yeast forms on methenamine silver stain of lung tissue |
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How do you treat a Pneumocystis jirovecii infection?
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- TMP-SMX
- Pentamidine |
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When should you do prophylactic treatment for Pneumocystis jirovecii? Regimen?
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- Start prophylaxis when CD4 counts drop <200 cells/mm3 in HIV patients
- Use Dapsone, Atovaquone, TMP-SMX, and Pentamidine |
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Which fungus typically presents in gardeners and causes a local pustule or ulcer with nodules along draining lymphatic (ascending lymphangitis)
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Sporothrix schenckii
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What is the appearance and location of Sporothrix schenckii?
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Dimorphic, cigar-shaped budding yeast that lives on vegetation
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How do you get infected with Sporothrix schenckii? Disease?
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- Spores are usually traumatically introduced into the skin, typically by a thorn ("rose gardener's disease")
- Causes Sporotrichosis → local pustule or ulcer with nodules along the draining lymphatics (ascending lymphangitis) - Little systemic illness |
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How do you treat Sporothrix schenckii?
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Itraconazole or POTassium iodide
(remember it is typically in rose gardener's - "plant a rose in the POT") |