Staphylococcus Aureus

Question 1

coagulase positive or negative

Answer 1

positive

Question 2

coagulase

Answer 2

the ability to clot

Question 3

pigment on agar

Answer 3

gold

Question 4

alpha, beta, or gamma hemolytic

Answer 4

beta hemolytic

Question 5

ferments….

Answer 5

manitol

Question 6

what type of media is mannitol-salt agar

Answer 6

selective and differential

Question 7

catalase positive or negative

Answer 7

positive

Question 8

catalase

Answer 8

breaks down H2O2 produced during oxidative metabolism

Question 9

beta lactamase positive or negative?

Answer 9

positive

Question 10

beta lactamase

Answer 10

resistant to penicillins and cephalosporins

Question 11

epidemiology

Answer 11

very contagious

Question 12

reservoir

Answer 12

humans are nasal carriers
- may also colonize skin and mucous membranes

Question 13

transmission

Answer 13

direct skin to skin contact
indirect contact via fomites
ingestion of contaminated

Question 14

major virulence factors

Answer 14

capsule
catalase
exotoxins
coagulase
staphylolusin
leukocidin
protein A
hyaluronidase

Question 15

catalase

Answer 15

neutralizes hydrogen peroxide
- counteracts phagocyte’s oxidative killing

Question 16

capsule

Answer 16

composed of polysaccharides
- inhibit phagocytosis

Question 17

staphylolysin

Answer 17

lysis red blood and white blood cells

Question 18

enterotoxin

Answer 18

potent gastrointestinal toxin as well as super antigen activity

Question 19

toxic shock syndrome toxin 1

Answer 19

act as a potent super antigen

Question 20

exfoliative toxin

Answer 20

an exotoxin that causes desquamation of the skin, weak superantigen activity

Question 21

protein A function

Answer 21

inhibits functions of antibodies
- does not allow binding to the virus

Question 22

hyaluronidase

Answer 22

degrades hyaluronic acid that cements cells together to promote spreading through tissues

Question 23

disease

Answer 23

skin diseases (including abscesses)
toxin-mediated :
- staphylococcal food poisoning
- scalded skin syndrome
- toxic shock syndrome

Question 24

infection

Answer 24

colonization

Question 25

intoxication

Answer 25

toxin production (outside of host)

Question 26

infection and intoxication

Answer 26

colonization and then toxin production (inside of host)

Question 27

pyogenic

Answer 27

pus producing

Question 28

pyogenic infections are characterized by the formation of an

Answer 28

abscess

Question 29

pathogenesis of S. aureus skin infections

Answer 29

enters through tiny break or opening in skin replicates and releases virulence factors that damage tissue and body responds inflammation (PMNs arrive and phagocytize bacteria and dead cells) cavity forms filled with pus cavity expands local fibroblasts lay down fibrin around pus filled cavity antibiotics alone can't penetrate the abscess so it requires drainage

Question 30

folliculitis

Answer 30

infection of hair follicle - resolves or progresses to furuncle

Question 31

furuncle

Answer 31

boil, large painful lesion that extends from hair follicle to surrounding tissues - resolves or progresses to carbuncle

Question 32

carbuncle

Answer 32

multiple interconnected abscesses forming from the aggregation of furuncle - requires debridement nad antibiotics

Question 33

impetigo

Answer 33

small flattened red patches -> pus filled vesicles -> rupture and crust over - common among infants and young children - itchy, highly contagious

Question 34

food poisoning

Answer 34

when it is caused by a toxin not an infection it is food poisoning - symptoms: nausea and vomiting (NO FEVER)

Question 35

staph food poisoning is an example of

Answer 35

intoxication

Question 36

staphylococcal enterotoxin

Answer 36

can cause food intonation - resistant to low pH - heat stable - superantigen activity

Question 37

why do you think blood cultures failed to isolate any pathogens

Answer 37

there were no bacteria in the blood samples because replicating bacteria were not causing the systemic disease

Question 38

toxic shock syndrome is an example of

Answer 38

infection and intoxication

Question 39

toxic shock syndrome

Answer 39

caused by toxic shock syndrome toxin 1 - incudes fever, vomiting, rash, and shock - act as a potent super antigen - causes 75% of all cases

Question 40

symptoms of toxic shock

Answer 40

abrupt onset of high fever red erythematous (sunburn-like) rash desquamation hypotension -> multi system organ failure

Question 41

staphylococcal scalded skin syndrome (SSSS)

Answer 41

localized infection, systemic intoxication - causes by exfoliative toxin (causes desquamation) - weaker than TSS-1

Question 42

symtoms of SSSS

Answer 42

erythema (redness) followed by desquamation no scarring typically affects neonates and infants potential complication

Question 43

potential complication of SSSS

Answer 43

a secondary infection of areas where the skin has peeled away

Question 44

management of staphylococcal infections

Answer 44

boils, carbuncles may require minor surgery to drain pus antibiotic treatment often follows debridement

Question 45

staylococci produce

Answer 45

penicillinase ( a type of beta lactamase)

Question 46

methicillin resistant S. aureus (MRSA)

Answer 46

these strains are resistant to beta lactic antibiotic, being sensitive only to vancomycin -associated with worse outcomes such as longer hospital and ICU stays and higher mortality rates