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Flashcards in Infectious Disease CPC Deck (15)
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How does an x-ray of a lung abscess look different from lobar pneumonia?

Lobar pneumonia rapidly fills up a whole lobe, while with a lung abscess from mixed aerobic/anaerobic bacteria, the dense consolidation doesn't fill up the entire segment of the lung


What is suspected from an x-ray that shows dense bilateral consolidation around the hilum of the lung?

Granulomatous inflammation


What is the etiology of an epithelioid granuloma? (2 causes)

Tuberculosis (rare in US)
Histoplasma capsulatum (yeast, with granulomas like those in TB)


How do the granulomas from histoplasmosis differ from those seen in TB?

They are much more fibrous


What is suspected from an x-ray that shows fluffy bilateral inflammation?

Interstitial inflammation


What can cause interstitial pneumonia? (4)

Mycobacteria (not TB) [2-8 wks]
Respiratory viruses [hours]
CMV (in immunosuppressed patients) [1 day]
Legionella pneumophila (-> Legionnaire's disease) [4 days]


What is the ONLY conclusion you can draw from a sputum stain that shows mixed bacterial populations and squamous cells?

The squamous cells and mixed bacteria COME from the upper respiratory tract
--Can't diagnose pneumonia or aspiration, not enough info


What is seen histologically in a lung with interstitial inflammation? (2)

Too many cells in alveolar wall
Foamy alveolar exudate with no inflammatory cells (clear on x-ray)


Characterize pneumonia caused by Pneumocystis jirovecii. (2)

Seen in highly immunosuppressed patients (opportunistic)
-> Interstitial pneumonia


Characterize skin lesions caused by Pseudomonas aeruginosa. (4)

Aka "Ecthyma gangrenosum"
Toxin-mediated necrosis and inflammation in dermis
Accompanied by bacteremia
Increased risk with neutropenia


Name and describe an organism that can cause pseudomembrane formation in the oropharynx. (3)

Candida albicans - budding yeast, pseudohyphae
-> Thrush, esophagitis
-> Acute supperative inflammation if there are enough white cells


What is seen histologically in an active CMV infection? (1) What about in the retina? (1)

Enlarged endothelial cells with prominent intranuclear inclusions (owl's eye)

Retina: fluffy white areas in peripheral fields


3 steps to diagnosis of active CMV disease:

Inclusions in tissue biopsy (gold standard)
Serologic evidence of exposure to CMV (positive IgG Ab)
Quantitative measure of CMV viral load via PCR of blood


What does it mean when you see multiple "ring enhancing" lesions at the gray/white junction in a CT scan of the brain?

Necrosis and acute inflammation due to Toxoplasma gondii


What would be seen histologically in encephalitis due to Toxoplasma gondii?

INTRAcellular parasites seen
Necrosis of neurons and microglial cells
Variable acute inflammatory reaction