1 - staphylococcus aureus

Question 1

microscopy

Answer 1

gram +ve cocci
grape like clusters

Question 2

cultivation

Answer 2

-easy to culture, non-fastidious
-produces golden colonies
-b-hemolytic
-ferments mannitol

Question 3

biochemical reactions

Answer 3

catalase +ve
coagulase +ve
ferments mannitol

Question 4

transmission

Answer 4

-contaminated food
-resp droplets

Question 5

skin and soft tissue infections (SSTI)

Answer 5

-impetigo
-folliculitis, carbuncle, furuncle
-abscess
-cellulitis
-wound infections

Question 6

systemic infections

Answer 6

-pneumonia
-osteomyelitis
-arthritis
-endocarditis
-sepsis

Question 7

toxin mediated disease

Answer 7

-toxic shock syndrome
-scalded skin syndrome
-food poisoning

Question 8

cellular virulence factor (4)

Answer 8

-capsule = polysaccharide, anti-phagocytic

-protein A = binding immunoglobulin by Fc part of IgG + biofilm formation

-specific adhesion proteins = fibrinogen, fibronectin, fibrin, collagen

-biofilm formation

Question 9

enzymatic virulence factor (6)

Answer 9

-DN -ase
-Lipase
-phosphatase
-hialuronidase
cause lysis of human tissue, necrosis
-coagulase; fibrin, causes masking
-fibrinolysnin: allows bacteria to spread

Question 10

virulence exotoxins

Answer 10

-hemolysins: lyse RBC
-panton-valentine leukocidin: kills WBC
-toxic shock syndrome toxin-1: cytokine release
-enterotoxin: food poisoning
-exfoliate toxin: causes scalded skin syndrome

Question 11

which are the superantigen toxins

Answer 11

-TSST-1
-enterotoxins
-exfoliative toxins

Question 12

diagnosis

Answer 12

-lab sample taken from pus, blood, aspirate

Question 13

what does the catalase test differentiate it from

Answer 13

-from streptococcus species

Question 14

what does the coagulase test differentiate it from

Answer 14

-from coagulase -ve staphylococci

Question 15

faster alternative to coagulase test

Answer 15

clump test
-latex agglutination

Question 16

treatment for
MSSA

Answer 16

based antibiogram
-B-lactamas: floxacillin, cephalosporins
or
clindamycin, fluoroquinolones

Question 17

treatment for
MRSA (4)
types of MRSA

Answer 17

-HA- MRSA: hospital acquired
-CA-MRSA: community acquired
-LA-MRSA: livestock associated

-vancomycin
-5th generation cephalosporins
-daptomycin
-linezolid