Staphylococcus Aureus

Question 1

Morphology

Answer 1

Gram Positive cocci in clusters
Golden color in culture
encapsulated, facultative anaerobe

Question 2

Classification/Diagnosis

Answer 2

Catalase Positive (Strep is negative)
Coagulase Positive
Grows on blood agar
test by gram stain and culture

Question 3

Pathology

Answer 3

Alpha-toxin (pore-forming)
Panton-Valentin leukocidin
Beta Toxin (damages cell membranes)
Toxic shock syndrome toxin
exfoliative toxin
enterotoxin
capsule

Question 4

Epidemiology

Answer 4

Colonizes skin, oropharynx, and urogenital tract

25% of adults are persistant carriers

Question 5

Diseases/symptoms

Answer 5

Scalded skin syndrome
food poisoning (incubation 4 hrs)
Toxic shock syndrome (cytokine storm, vascular collapse, peeling skin)
cutaneous infections (impetigo, folliculitis, carbunclesO
bacteremia, endocarditis, pneumonia secondary to flu, emphyema, osteomyelitis, septic arthritis

Question 6

Treatment/Vaccination

Answer 6

methicillin/oxacillin for MSSA

Vancomycin for MRSA (resistance to all beta-lactams, due to altered PBP - penicillin binding protein)