Block Intro

Question 1

Recall that endotoxin is only found in ________________.

Answer 1

Gram-negative organisms (because endotoxin is the outer membrane)

Question 2

What surface protein is only found in Gram-positive organisms?

Answer 2

Teichoic acid

Question 3

Which two bacteria do not Gram stain because they lack cell walls?

Answer 3

Mycoplasma and Chlamydia

Question 4

True or false: of the Gram-positive cocci, only Streptococcus forms pairs.

Answer 4

False. Both Staphylococcus and Streptococcus form pairs, but Staphylococcus forms pairs in clusters and Streptococcus forms pairs in chains.

Question 5

If a culture comes back positive for coagulase-negative Staphylococcus, it is most likely ________________.

Answer 5

contamination from S. epidermidis (that does not require treatment); the only exception is if the patient has a prosthetic implant, such as a dialysis catheter or artificial heart valve

Question 6

Which Streptococci are alpha hemolytic, beta hemolytic, and gamma hemolytic?

Answer 6

Alpha: S. pneumoniae and S viridans (think of viridans coming from the Latin for green, which is how alpha hemolysis presents)

Beta: S. pyogenes and S. agalactiae (think of the beta bulb in the bakery and the beta bulb on the UFO on the moon base)

Gamma: S. milleri

Question 7

Which is worse, endocarditis from S. aureus or S. viridans?

Answer 7

S. aureus

In fact, S. viridans is surprisingly mild. Mahler had S. viridans endocarditis for months.

Question 8

What infection do anaerobes often cause?

Answer 8

Intestinal (particularly Bacteroides fragilis) and female GU

Question 9

What three categories of factors determine the outcome of an infectious disease?

Answer 9

Host factors (e.g., immune capacity)
Agent factors (e.g., virulence and resistance) 
Environmental factors (e.g., crowding, pollution, sanitation)

Question 10

What are the attachment sites for capsules in Gram-negative and Gram-positive organisms?

Answer 10

Gram-positive: peptidoglycan wall

Gram-negative: outer membrane

Question 11

What is a mnemonic for Gram staining?

Answer 11

H VIAS
Heat
Violet
Iodine
Alcohol (decolorizer) 
Safranin

Question 12

Sketchy is great about keeping the symbol for encapsulation consistent, but what are some exceptions?

Answer 12

Bacillus (in which the Viking armor represents a capsule) and Streptococcus pneumoniae (in which the knight’s armor represents the capsule)

Question 13

What kind of bacteria is Moraxella?

Answer 13

Gram-negative diplococci

Question 14

Which Gram-negative rod is indole positive?

Answer 14

E. coli

Question 15

The top cause of death from infectious disease (meaning the type of infection, not a specific organism) is _____________.

Answer 15

pneumonia