Sketchy Micro: Nocardia

Question 1

What kind of bacteria is Nocardia asteroides?

Answer 1

Like Actinomyces israelii, it is a Gram-positive filamentous rod (think of the painting of the desert tree with the branches). Unlike A. israelii, however, N. asteroides is an obligate aerobe (think of the bellows on the bar).

Question 2

Nocardia asteroides is usually found in the ________.

Answer 2

soil (like the broken cactus pots on the table where the cowboy is crouching)

Question 3

Bacteria will stain for acid fast when they have __________.

Answer 3

mycolic acid

Question 4

What lab tests can help identify N. asteroides?

Answer 4

• Acid-fast positive (like the cowboy’s dangling strings that look like tassels and his fuchsia gun –because AF stains fuchsia)
• Catalase positive (like the cat on the bar)
• Urease positive (like the NH3 bottle –which looks like the one we spray Walter with! –on the bar)

Question 5

Nocardia is especially common in ___________ patients.

Answer 5

immunocompromised (like the cowboy with the cane –he’s physically compromised, in a way)

Question 6

What three infection sites are most common for Nocardia?

Answer 6

• Pneumonia, forming cavitary lesions (like the caved-in badge that’s being shot on the cowboy’s vest)
• Brain abscesses (the hole in the cowboy’s hat)
• Cutaneous lesions (like the inflamed, indurated cow-print on the cowboy’s suit)

Question 7

How should you treat Nocardia infections?

Answer 7

Sulfonamides (think of the rotten eggs on the bar)