strep + enterococcus

Question 1

1. Name the species of streptococci associated with Lancefield groups A and B.

Answer 1

A - pyogenes

B - agalactica

Question 2

2. Describe the structural and functional characteristics that distinguish streptococci from
   staphylococci

Answer 2

Catalase negative

Chains and pairs

Question 3

3. List six clinical manifestations of Streptococcus pyogenes infection.

Answer 3

Acute Pharyngitis (5-15 y/o, sore throat, headache, swollen lymph nodes)

Scarlet fever (erythrogenic exotoxin-> sore throat, fever, “strawberry” tongue, rash begins to fade three to four days after onset and desquamation begins)

Impetigo (2-5 y/o, trauma/insect bites, pustule w/ yellow crust)

Toxic shock–like syndrome

Erysipelas (speading erythema with well demarcated edge on the face, Fever, lymphadenopathy steptococcal pharyngitis)

Necrotizing Fasciitis (strep in subcutaneous tissues, destruction of muscle and fat, systemic toxicity)

Puerperal Sepsis (seen in women following delivery or abortion. organisms colonizing genital tract invade upward–> endometritis, lymphangitis, bacteremia, necrotizing fasciitis, and streptococcal TSS)

Question 4

4. Name two diseases that occur as sequelae to streptococcal infections and describe their
   clinical presentation

Answer 4

Rheumatic fever:
J- joints, polyarthritis 
O-(heart shaped) heart problems
N-nodules - subcutaneous, forearms,
E-erythema marginata - red rash
S- Sydenham's chorea, rapid movements

Glomerulonephritis
Follows impetigo and pharyngitis

Question 5

5. Name four virulence factors associated with Streptococcus pyogenes and the
   mechanisms by which they enhance infection

Answer 5

Adherence (M protein) - highly antigenic, responsible for rheumatic fever, anti-phagocytic
Invasion (Streptokinase, streptolyisns)
Avoid opsonization and phagocytosis (Hyaluronidase, hemolysins, capsular polysaccharide)
Toxins and enzymes (Nucleases, C5a peptidase, pyrogenic exotoxins)

Lipoteichoic acid

Question 6

6. Describe the limitations for Rapid Group A Detection kits.

Answer 6

0

Question 7

7. Explain the role of Streptococcus agalactiae in causing neonatal disease and how
   neonatal disease may be prevented.

Answer 7

Leading cause of neonatal meningitis, important cause of sepsis and pneumonia.

Can be prevented via testing pregnant women at 35-37 weeks gestation (vaginal and anal swab). If test comes back positive, treat mother prophylactically with penicillin

Question 8

8. Name the species included in the Strep Milleri Group and Nutritionally deficient Strep Group

Answer 8

Strep. milleri: anginosis, constellatus, intermedius

Nutritionally-deficient strep: abiotrophia, granulicatella

Question 9

9. List the two major species of Enterococus causing infection in humans and explain their association with penicillin (or ampicillin) susceptibility and resistance.

Answer 9

E. faecalis - pen/amp susceptible

E. faecium - pen/amp resistant

Question 10

10. List the 3 most common infections caused by Enterococcus species.

Answer 10

Urinary tract
Sepsis
Endocarditis

Question 11

11. Identify the key morphologic and phenotypic tests used for identification of S. pneumoniae

Answer 11

Alpha-hemolysis
G+, catalase negative
Optochin sensitive
Bile soluble
Lancet-shaped