Sketchy Micro: Staph Aureus

Question 1

What does Staphylococcus aureus mean, etymologically, and how does that help you remember some of its key features?

Answer 1

Staphylococcus = bunch of grapes, which is what it looks like under the microscope

Aureus = golden, because it looks golden on a blood agar plate

Question 2

Staphylococci are Gram-_____________.

Answer 2

positive (just like Moses’ violet robes)

Question 3

Staphylococci are catalase-_____________.

Answer 3

positive (just like the Egyptian cat next to Moses)

Question 4

Staphylococcus aureus is coagulase-____________.

Answer 4

positive (just like the coagulated blood in the sea that Moses is parting; this should also help you remember that coagulase converts fibrinogen to fibrin)

Question 5

True or false: Staphylococcus aureus is beta-hemolytic.

Answer 5

True! (Just think of Moses holding that lightbulb that looks like a red agar dish with the golden hemolysis–the filament is beta-shaped.)

Question 6

Bacteria that can ferment mannitol turn it _____________.

Answer 6

yellow (from red); S. aureus does this, which Sketchy symbolizes by the TaLl MAN (mannitol) behind Moses

Question 7

Explain how the main virulence factor of S. aureus works.

Answer 7

S. aureus secretes protein A, which binds the Fc region of antibodies and prevents opsonization.

(Think of the A on Moses’ staff and how it is grabbing the amulet that looks like an antibody.)

Question 8

S. aureus typically colonizes the ____________.

Answer 8

nares (just like the sphynx’s nose, chopped off and sitting over by Moses)

Question 9

What pneumonia presentation does S. aureus typically present with?

Answer 9

A secondary infection after a viral respiratory illness (think of the icosahedral lamps to remind you of the virus) with patchy infiltrate (like the patchy blanket on the coughing camel)

Question 10

What disease is Sketchy making you remember with the bandages on the camel’s knees?

Answer 10

Septic arthritis –S. aureus is the most common cause of septic arthritis

Question 11

What heart problem can S. aureus cause?

Answer 11

Acute bacterial endocarditis (often right-sided, tricuspid infections in drug users)

(Think of the woman riding the camel who is ACUTEly running with heart emblems and the mortar and pestle symbolizing drug use.)

Question 12

S. aureus is the most common cause of what disorder symbolized by the fishbones?

Answer 12

Osteomyelitis (like, old nasty fishbones)

Question 13

Exfoliative toxin (from S. aureus) can cause what disease?

Answer 13

Scalded skin syndrome (represented by the bald guy with the horrible sunburn)

Question 14

What is TSST?

Answer 14

Toxic shock syndrome toxin –a toxin secreted by S. aureus that binds MHC and TCRs non-specifically to stimulate cytokine storm

Question 15

Preformed toxin from S. aureus can cause _______________.

Answer 15

acute food poisoning, commonly from rancid dairy or meats

Think of the woman on the rushing camel about to puke; she has meats and dairy strapped to the camel.

Question 16

How does S. aureus become resistant to penicillin?

Answer 16

It alters its penicillin-binding proteins (those that help make the cell wall).

(Think of the altered Pyramid-Building People that the MeRciful pharaoh had to use when the slaves left.)

Question 17

How should you treat MRSA or MSSA?

Answer 17

MRSA: vancomycin (like the caraVAN)
MSSA: Nafcillin (“Naf for Staph!” Also, think of the pencil in the pharaoh’s hand.)