Bacterial Infections

Nocardial microabscess

Abscesses are walled-off areas of destructive (necrotizing) pneumonia. Here, the pink fibrous wall surrounds a mixture of blood and pus centrally.

Nocardia asteroides

A gram stain (left) of the abscess shows thin, gram positive rods in chains. An acid fast stain (right) was also positive.

Aspiration pneumonia--pulse

Aspirated food particles include pulses--seeds of leguminous plants (e.g., beans). Many food particles incite a granulomatous reaction, as shown here. Note the multinucleated giant cell near the top. The bean particles (arrow shows one) have a carbohydrate component, which stains with PAS (inset).

See also Case 28

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