staphylococci

Question 1

staphylococci aureus: histology + character

Answer 1

gram positive streptococci in clusters; catalase positive and coagulase positive

common carriers have s.aureus on the anterior nares

not normal flora

Question 2

staphylococci aureus: culture

Answer 2

golden yellow colonies cultured on blood agar

Question 3

staphylococci aureus: transmission

Answer 3

direct or indirect contact

Question 4

staphylococci aureus: virulence factors

Answer 4

protein A binds to the Fc portion of IgG and prevents opsonisation

extracellular proteins (enzymes): - leukocidin destroys phagocytes

extracellular proteins (exotoxins): - epidermolysins that cause skin and soft tissue infection (staphylococcal scalded skin syndrome, ritter’s disease), enterotoxins that cause food poisoning, toxic shock syndrome toxin-1

Question 5

staphylococci aureus: clinical presentations

Answer 5

skin and soft tissue infections: furuncles, carbuncles, cellulitis and impetigo (can be caused by s.pyogenes), ssss

food poisoning
toxic shock syndrome
pneumonia
endocarditis
deep infections including osteomyelitis and septic arthritis

Question 6

staphylococci aureus: diagnosis

Answer 6

pus/blood

histological (microscopy), culture

Question 7

staphylococci aureus: treatment

Answer 7

incision and drainage before treatment with antibiotics - cloxacillin and flucloxacillin

mrsa can only be treated with ceftabiprole, ceftaroline, vancomycin

Question 8

name the 3 coagulase negative staphylococci

Answer 8

staphylococci lugdunensis
staphylococci epidermis
staphylococci saprophyticus

Question 9

staphylococcus lugdunensis

Answer 9

normal perineal flora

produces biofilm

Question 10

staphylococcus saprophyticus

Answer 10

normal vaginal flora

causes UTI in sexually active young women