Week 3: Staph

Question 1

List pathophysiologies of S. aureus

Answer 1

• Folliculitis
• Boils (furuncles)
• Carbuncles (big boils)
• Bullous impetigo (giant ruptured crusty stuff)
• Scalded skin syndrome
• Toxic shock syndrome
• Food poisoning
• meningitis
• UTI
• osteomyelitis
• sepsis
• mastitis

Question 1

List some S. aureus virulence factors

Answer 1

• Protein A
• Hyaluronidase
• Coagulase

Question 2

List methods to detect MRSA

Answer 2

• Nucleic acids probes/ PCR to detect mecA gene (gold standard
• CHROMagar MRSA
• Latex agglutination or EIA
• Oxacillin screen agar
• Cefoxitin disk

Question 3

Describe D-test

Answer 3

Check for macrolide resistance of clindamycin by putting erythromycin disk next to clindamycin disk. Inducible clindamycin resistance results in D shape zone of inhibition

Question 4

Sources of S. aureus?

Answer 4

Any clinical specimen

Question 5

Sources of coag neg staph?

Answer 5

• Normal skin flora + mucous membranes
• Often hospital acquired

Question 6

S. epidermidis virulence factors

Answer 6

• Capsule can help adhere to surfaces (helps with biofilms)
• Extracellular slime substance for biofilms

Question 7

List pathophysiologies of S. epidermidis

Answer 7

• subacute endocarditis
• meningitis involving shunts
• Prosthetic device-associated infections
• Post-op surgical infections

Question 8

Pathophysiology of S. saprophyticus

Answer 8

UTIs

Question 9

List pathophysiologies of S. lugdunensis

Answer 9

• Endocarditis
• Skin + soft tissue infections