Olson- Staphylococcus and Streptococcus

Question 1

What is the main cytotoxic agent produced by s. aureus? How does it exert it’s effects?

Answer 1

Alpha-toxin (alpha-hemolysin)

Causes pores on cells, which leads to cell death

Question 2

What are some of the enterotoxins produced by s. aureus? What diseases do they cause?

Answer 2

TSST- Toxic shock syndrome

Exfolatin- Scalded skin syndrome

Enterotoxins- Food poisoning

Question 3

What is an example of a spreading factor produced by s. aureus?

Answer 3

Hyaluronidase

Question 4

What are 4 evasion strategies by s. aureus?

Answer 4

Inhibition of neutrophil chemotaxis
-CHIPS (Chemotaxis inhibitory protein) binds C5a and F-MP on neutrophils

Resistance to phagocytosis
-Coagulase coats the bacteria in fibrin and prevents its phagocytosis

Resistant to antimicrobial peptides
-Antimicrobial peptides use their negative charges to disrupt the lipid membrane, but teichoic acid on staph. aureus is charged and repels it

Survival inside of neutrophils
-catalase, superoxide mutase and staphyloxanthin all help s. aureus survive oxidation

Question 5

What is the main virulence factor of s. pyogenes? How does it exert it’s effects?

Answer 5

M protein

Destroys C3 convertase, preventing the opsonization of C3b

Question 6

What are some examples of diseases caused by s. pyogenes?

Answer 6

Pharyngitis
Impetigo
Scarlet fever
Erysipelas
Cellulitis
Necrotizing fasciitis 
Post-infection diseases like rheumatic fever and acute glomerulonephritis

Question 7

What is an example of a group B strep pathogen, and what diseases would it cause?

Answer 7

S. agalactiae

Neonatal sepsis and meningitis

Question 8

What is an example of group C strep and what diseases would it cause?

Answer 8

S. dysgalatiae

Causes pharyngitis, but does not have the wide array of diseases that s. pyogenes has

Question 9

What hemolytic group would s. viridians fall into? What disease is it heavily associated with?

Answer 9

S. viridians is alpha hemolytic and causes 30-40% of all sub-acute bacterial endocarditis cases

Question 10

Patients with colon cancer can develop what diseases due to what type of streptococcus?

Answer 10

Endocarditis and bacteremia

S. bovis

Question 11

What diseases can streptococcus pneumoniae cause?

What is it’s main virulence factor?

Answer 11

Community acquired pneumonia

Adult meningitis

Sinusitis

Otitis media

Main virulence factor: Polysaccharide capsule

Question 12

What diseases does enterococcus cause?

Answer 12

Endocarditis, UTI’s, bacteremia