lab notes 7

Question 1

nose sampling

Answer 1

sample with sterile cotton swab; streak onto a mannitol-salt-agar (MSA)

Question 2

mannitol- salt-agar is

Answer 2

selective (7.5% NaCl) differential (mannitol) medium

Question 3

throat sampling

Answer 3

use sterile tong depressor and sterile cotton swab; streak onto blood agar plate

Question 4

staphylococcus features

Answer 4

coccus shaped, gram (+), catalase positive, aerobic or facultative bacteria

Question 5

staphylococcus relevant genera

Answer 5

Staphylococcus - tolerate up to 10% salt, facultative, 32 spp.
Micrococcus - aerobic, 2 spp.
Stomatococcus - 1 sp., commensal, mucoid capsule
Alloiococcus - middle ear infections in children

Question 6

Staphylococcus virulence determinates

Answer 6

capsule, cell wall, protein A, coagulase, and other surface proteins

Question 7

S. aureus is

Answer 7

Staphylococcus aureus

Bacteria

Question 8

Coagulase is

Answer 8

an enzyme that clots

blood plasma and a virulence factor of S. aureus

Question 9

Coagulase-positive test

Answer 9

is performed to identify coagulase

positive Staphylococcus aureus

Question 10

formation of a clot around an infection

Answer 10

protects the bacterium from phagocytosis

Question 11

preforming a coagulase-positive test

Answer 11

add 500 μl citrated plasma into a small culture tube
with a loop add a half of a pea-size colony
mix well
incubate in a 50 ºC water bath for 60 min
observe the coagulase reaction