Micro/Immuno Flashcards
(71 cards)
Contained infection by this is called “valley fever” or “desert rheumatism”
What is it?
Coccidioides immitis
Pathogenesis of Histoplasma capsulatum involves what immune cell? How?
Macrophages – engulfs spores, which survive by producing bicarb and ammonia to raise pH and inactivate hydrolytic enzymes.
Immunocompromised geriatric patient has cough, chest pain, hemoptysis, weight loss, other flu-like symptoms, and ulcerated lesions on tongue. Exam/Lab/Imaging/Biopsy: cavitary lung lesions, granulomas in liver and spleen, pancytopenia.
What is it?
Histopalsmosis (H. capsulatum)
A patient has a fungal infection that requires treatment w/ amphotericin B, but he has kidney problems.
What do you do?
Give liposomal form of Amphotericin B
Histoplasma capsulatum has 2 types of asexual spores:
Tuberculate macroconidia and Microconidia.
–Which type is infectious?
–Which type has thicker walls?
–Which type has Fingerlike projections?
–Which type can be grown in 25C Sabouraud’s agar?
- -Infectious = microconidia
- -Thicker = tuberculate macroconidia
- -Projections = tuberculate macroconidia
- -Agar = tuberculate macroconidia
(unexposed/contained/disseminated/cleared) Coccidoides:
PPD w/ coccidioidin or spherulin:
–When is it (+)?
–When is it (-)?
(+) = exposed w/ cleared or contained infection
-) = unexposed, disseminated infection (in immunosuppressed
What are red, tender nodules on exterior surfaces like lower legs that develop due to cell-mediated hypersensitivity to fungal antigens?
Erythema nodosum
What are the 4 Systemic Mycosis organisms?
- Coccidioides immitis
- Histoplasma capsulatum
- Blastomyces dermatitidis
- Paracoccidioides brasiliensis
Which systemic mycosis has the following endemic areas:
- -Eastern North America and Great Lakes region?
- -Rural Latin America?
- -Ohio and Mississippi River valley?
- -Southwest US, Latin America?
Blastomyces dermatitidis
Paracoccidioides brasiliensis
Histoplasma capsulatum
Coccidioides immitis
What dimorphic fungus has a mold for that is hyphae w/ small pear-shaped conidia and a yeast form w/ doubly refractive wall and a single broad-based bud?
Which form is found in tissue vs. culture?
Blastomyces dermatitidis
- -Tissue biopsy –> yeast cells
- -Culture –> hyphae
What dimorphic fungus has a mold for w/ thin, septate hyphae and a yeast form that is thick-walled w/ multiple buds?
Paracoccidioides brasiliensis
What are the 5 Opportunistic Mycosis organisms/groups?
- Candida
- Cryptococcus neoformans
- Aspergillus fumigatus + others
- Mucor/Rhizopus
- Fusarium spp
An AIDS patient accidentally ingests bird poop (specifically pigeon).
What mycosis is he at risk for?
Cryptococcus neoformans
Patient w/ Hx of steroid use, malignant disease, previous transplant, and HIV+ has a slight fever and slight stiff neck w/ subcutaneous nodules. Lab: CSF stain w/ India ink shows yeast w/ wide capsule. Serology: CrAg.
What is it?
Cryptococcus neoformans
Culture shows: mold only – septate hyphae w/ V-shaped branches, conidia forming radiating chains.
What is it?
Aspergillus fumigatus
- -Virulence factors: gliotoxin (immunosuppressive), toxic metabolites, proteases
- -Impairs macrophage and neutrophil responses
- -Airborne infectious conidia
- -Colonizes abraded skin, burns, cornea ,ear, sinuses
What is it?
Aspergillus fumigatus
Patient w/ asthma and CF has coughs of brownish substance w/ blood in sputum, fever, wheezing. Doesn’t respond to Abx. CXR: “grape cluster”/”hand in mitten” clusters in bronchi. Labs: Eosinophilia, high IgE. Treated w/ omalizumab and sinus surgery.
What is it?
Pathogenesis?
–Allergic bronchopulmonary aspergillosis (ABPA)
- -Hypersensitivity to bronchi infection by aspergillus.
- -Exacerbates asthma, CF
Patient w/ Hx of alcoholism, collagen-vascular disease, chronic granulomatous disease, COPD, and long-term corticosteroid use has subacute pneumonia (ineffective Abx), fever, cough, night sweats, weight loss, and ineffective TB treatment.
What is it?
Pathogenesis?
–Chronic necrotizing pulmonary aspergillosis (CNPA)
- -Hyphae invade lung tissue –> pneumonia w/ hemoptysis and granulomas
- -Rare, hard to diagnose
Patient w/ Hx of TB and CF has cough, fever, severe hemoptysis. CXR: fungus ball that changes position when sitting up vs. lying down.
What is it?
Pathogenesis?
–Aspergilloma
- -Fungus balls form at site of cavitary lesion left by past TB, pulmonary mycosis, or CF.
- -Can cause lethal pulmonary hemorrhage
Patient w/ Hx of COPD on corticosteroids and A LOT of immunosuppressives has fever, cough, pleuritic chest pain, worsening hypoxemia. Chest CT: “halo sign”. Labs: high serum glactomannan antigen.
What is it?
Pathogenesis?
–Invasive aspergillosis
- -Rapid, progressive invasion of blood vessels –> infarction, hemorrhage, necrosis
- -“Halo sign” = pulmonary infarction surrounded by alveolar hemorrhage
Patient w/ Hx of DM, burns, leukemia, IV steroids, TNFa blocker, or iron overload has and infection that causes brain, eyes, lungs, skin, GI or CNS failure due to impaired blood flow. Biopsy: nonseptate hyphae w/ broad irregular walls, branches at right angles
What is it?
–Mucor/Rhizopus/Absidia
Where might an infection by Fusarium spp develop in an immunocompetent patient?
Treatment?
–Under fingernails or in the cornea
–Amphotericin B, voriconazole, posaconazole
What is the most common Fusarium organism for both corneal and disseminated infections?
Fusarium solani
Fusarium microscopic morphology:
Banana-shaped macroconidia w/ “foot cell” at base
