Sketchy Micro: Histoplasmosis

Question 1

Histoplasma is almost always associated with ______________.

Answer 1

bird or bat droppings –such as a patient who spelunks

Think of the bats in the HISTOrian’s cave.

Question 2

Where (in the U.S.) is Histoplasma commonly found?

Answer 2

In the Mississippi Valley (like the map with the Mississippi highlighted and the fact that this is INDIANA Jones’ dorky brother)

Question 3

How do Histoplasma infect people?

Answer 3

People inhale spores and the fungi then infect macrophages (like the bird in the macrophage cage symbol next to the guy coughing).

Question 4

How can Histoplasma be diagnosed?

Answer 4

With urine or serum antigen tests (like the red and yellow dripping stalagtites)

Question 5

On KOH staining, Histoplasma appear as ______________.

Answer 5

small ovoid bodies inside macrophages (like the smaller puddles inside the larger puddles on the cave floor)

Question 6

Histoplasma is dimorphic, meaning _______________.

Answer 6

it is a “mold in the cold and a yeast in the heat”

Think of the dimorphic butterfly.

Question 7

What systemic signs does Histoplasma cause?

Answer 7

• Lung calcifications (like the white stalactites on the wall that looks like lungs)
• Erythema nodosum (like the red spots on the pillars that resemble legs)

Question 8

What does Histoplasma do in immunocompromised people?

Answer 8

It spreads to the liver and spleen and causes calcifications (like the cave painting of the bull with the liver and spleen spots above the historian’s cane).

Question 9

What two drugs treat Histoplasmosis?

Answer 9

• Ketoconazole or fluconazole for local infections (like the pine cones)
• Amphotericin for systemic infections (like the frog painting beneath the bull painting)