Sketchy Micro: Escherichia Coli (EHEC and ETEC)

Question 1

E. coli is a _____________.

Answer 1

Gram-negative rod

Question 2

What lab tests can help identify E. coli?

Answer 2

E. coli ferments lactose, so it grows on MacKonkey agars.

Think of the carton of milk on the bar.

Question 3

E. coli is _____________, and this expresses the _____ antigen.

Answer 3

encapsulated; K

Think of the glass case around the cake with the letter K on it.

Question 4

E. coli is __________-positive.

Answer 4

catalase (represented by the cat on the bar stool)

Question 5

E. coli grows __________ on EMB agar.

Answer 5

green (like the green coasters that the drinks are sitting on)

Question 6

E. coli’s ___________ allow it to cause UTIs.

Answer 6

fimbriae (think of the long bows above the glass that looks like a bladder)

Question 7

The milkshake symbolizes that ______________.

Answer 7

E. coli is the number-one cause of sepsis

Question 8

The capsular K antigen allows E. coli to _____________.

Answer 8

cause neonatal meningitis (like the helmet the baby is wearing while he reaches for the K cake)

Question 9

What lab test distinguishes EHEC from other strains of E. coli?

Answer 9

It does not ferment sorbitol.

Think of the “Sorbitol Free” soda in front of the little boy with the spilled, enterohemorrhagic ketchup.

Question 10

The toxin that EHEC secretes is similar to _______________.

Answer 10

Shiga toxin; in fact, it’s called Shiga-like toxin. Thus, it also inhibits the 60S subunit of ribosomes

(Think of the EHEC boy’s She-Gorilla action figure.)

Question 11

ETEC is most commonly transmitted via ____________.

Answer 11

contaminated water (like the water truck)

Question 12

ETEC has two toxins. What does each do?

Answer 12

The heat Labile toxin increases intracellular cAmp, and the heat Stabile toxin increases intracellular cGmp.

(Think “eL Agua de San Gabriel.”)