Streptococci and Enterococci

Question 1

What are 2 key features of Streptococci?

Answer 1

1) catalase NEG

2) cocci in pairs and chaines (strep is a strip)

Question 2

________ are aerobic while _____________ are anaerobic

Answer 2

staph (aero)

strep (anaero)

Question 3

How do you know if an organism is catalase positive or negative?

Answer 3

catalase positive - O2 bubbles up

Question 4

What are the 3 hemolytic properties of strep?

Answer 4

1) COMPLETE hemolysis (beta)
2) incomplete hemolysis (alpha)
3) NO hymolysis (gamma)

Question 5

What is the important strep species of Group A?

Answer 5

streptococcus pyogenes

Question 6

What is the important strep species of Group B?

Answer 6

streptococcus agalactiae

Question 7

What kind of infections are associated with S. pyogenes?

Answer 7

1) ACUTE PHARYNGITIS (resp droplets, 5-15 year old with fever, sore throat, headache, swollen lymph nodes)
2) IMPETIGO (2-5 child with localized skin disease)
3) ERYSIPELAS (spreading erythema with well demarcated edge on face or legs, fever and lymphadenopathy)
4) SCARLET FEVER
5) NEC FASC

Question 8

What are 7 clinical manifestations of strep pyogenes infection?

Answer 8

1) Acute pharyngitis
2) Impetigo
3) Erysipelas
4) Scarlet fever
5) Nec fas
6) Toxic shock-like syndrome
7) Puerperal sepsis

Question 9

What two bacteria can cause toxic shock?

Answer 9

staph and strep (group A)

Question 10

Which toxic shock like syndrome toxins belong to staph? strep?

Answer 10

staph = TSST-1
strep = SPE

Question 11

What patient population do you see puerperal sepsis?

Answer 11

women following delivery

bacteria from genital tract or obstetric personnel invade upper genital tract

Question 12

What are dangerous sequelae after strep?

Answer 12

Rheumatic fever (1-5 weeks after)

Acute glomerulonephritis (antigen+antibody+C deposited in glomeruli)

Question 13

Why can rheumatic fever be dangerous?

Answer 13

cardiac lesions called Aschoff bodies and vascular damage leads to possible endocarditis later in life

Question 14

What are 4 accomplishments of group A strep that help promote virulence?

Answer 14

1. adhere to surface of host cells
2. invade epithelial cells
3. avoid opsonization/phagocytosis
4. produce variety of toxins/enzymes

Question 15

What are the 7 S. pyogenes virulence factors?

Answer 15

Capsular polysaccharide
lipoteichoic acid
hemolysins
streptokinase
hyaluronidase
nuclease
C5a peptidase

Question 16

What are the 2 hemolysins of S. pyogenes?

Answer 16

Streptolysin S (oxygen stable, non-antigenic)
Streptolysin O (oxygen labile, ASO antibodies)

Question 17

What is SPE?

Answer 17

streptococcal pyrogenic exotoxins

superantigens of s. pyogenes; stimulate cytokine response leading to shock
responsible for rash in scarlet fever (erythrogenic exotoxin)

Question 18

What protein is absolutely required for the pathogenesis of s. pyogenes?

Answer 18

M protein

Question 19

What does the M protein do?

Answer 19

• binds to epidermal cells
• allows bacteria to survive
• antiphagocytic
• degrades complement C3b

Question 20

What 2 proteins of s. pyogenes allows for spread of bacteria in tissues?

Answer 20

streptolysins

streptokinase

Question 21

True or false: there are antibiotic resistant strep pyogenes?

Answer 21

FALSE

Question 22

What drugs do you use to treat s. pyogenes?

Answer 22

penicillin/ampicillin/amoxacillin

cephalosporins

erythromycin (for pen allergic patient)

Question 23

What does strep agalactiae cause?

Answer 23

• neonatal pneumonia, sepsis, meningitis
• skin/wound infections in adult diabetic patients
• endocarditis

Question 24

Is strep agalactiae normal on the body anywhere?

Answer 24

throat, vaginal and GI tract

Question 25

How can baby get GBS (group b strep)?

Answer 25

normal maternal colonization of vagina or rectum exposes baby at delivery leads to meningitis, bacteremia, pneumoniae

Question 26

How do you prevent babies from getting GBS at delivery?

Answer 26

culture mom at 35-37 weeks and treat mom as if she is positive

Question 27

How do you treat GBS?

Answer 27

penicillin/ampicillin gentamicin to enhance killing clindamycin for pen allergic

Question 28

Aside from s. pyogenes and s. agalactiae, what are the other beta hemolytic strep?

Answer 28

``` Group C (vet infections, pharyngitis in college kids, sepsis) Group F (abscesses) Group G (pharyngitis, sepsis in neonates) ```

Question 29

How do you diagnose GBS?

Answer 29

antigen test culture identification antibody detection (ASO, Anti-DNase)

Question 30

True or false: if GBS strep test comes up negative, pt is negative

Answer 30

FALSE; always do a back up culture

Question 31

What are Viridans Streptococci?

Answer 31

alpha or gamma hemolytic (NO BETA) major cause of dental caries important cause of endocarditis causes sepsis in neutropenic cancer patient

Question 32

What are the 5 groups of viridans strep?

Answer 32

- sanguis - mitis - mutans - salivarius - bovis

Question 33

What is included in the bovis group? What does it cause?

Answer 33

non-enterococcal group D strep bacteremia, meningits, endocarditis

Question 34

Isolation of s. bovis from blood is associated with what?

Answer 34

carcinoma of colon

Question 35

What bacteria has butterscotch scent on agar plates? also requires CO2 for isolation and makes pinpoint colonies

Answer 35

strep milleri

Question 36

Where are strep milleri infections usually found?

Answer 36

brain absecesses | cause pyogenic infections of cardiac, abdominal, skin and CNS tissues

Question 37

Where is strep milleri usually found?

Answer 37

mouth, oropharynx, GI tract, vagina

Question 38

Where is strep pneumoniae usually found?

Answer 38

upper resp tract

Question 39

What can strep pneumo cause?

Answer 39

- pneumonia - paranasal sinusitis - otitis media - meningitis - osteomyelitis - septic arthritis - endocarditis - peritonitis - cellulitis

Question 40

For which bug is a polysaccharide capsule important virulence factor?

Answer 40

strep pneumoniae

Question 41

Name the 5 virulence factors of strep pneumoniae

Answer 41

- pneumolysin - neuraminidase - phosphorylcholine - sIgA protease - Teichoic acid/peptidoglycan

Question 42

What does sIgA protease do?

Answer 42

prevent IgA mediated binding of pneumococcal cells to mucus

Question 43

What does teichoic acid/peptidoglycan do?

Answer 43

activates complement by alt pathway --> mediates inflammation

Question 44

What is the most common cause of CA acute bacterial pneumonia? Also most common cause of bacterial meningitis

Answer 44

s. pneumoniae

Question 45

What is responsible for the highest rate of meningitis in kids under 2?

Answer 45

s. pneumoniae

Question 46

What does s. pneumoniae look like?

Answer 46

gram+ lancet shaped cocci diplococci

Question 47

What does s. pneumoniae look like on blood agar?

Answer 47

dimes, alpha hemolytic

Question 48

What inhibits s. pneumoniae growth in the lab?

Answer 48

optochin

Question 49

How do you decide how to treat strep pneumococcal infections?

Answer 49

look at MIC for susceptibility

Question 50

What 3 drugs can you give for susceptible pneumococcal infections?

Answer 50

penicillin cefotaxime ceftriaxone

Question 51

What are some characteristics of enteroccus?

Answer 51

``` gram+ pairs short chains group D PYR pos a, B, y hemolytic ```

Question 52

What are the 2 classes of entercoccus virulence factors?

Answer 52

1) colonization - aggregation substance - carbohydrate adhesins 2) secreted - cytolysin - pheromone - gelatinase

Question 53

true or false: there are some vancomycin resistant enterococci

Answer 53

TRUE (E. faecium) Van A - plasmid mediated Van B - chromosomal Van C - intrinsic Makes YELLOW colonies

Question 54

What are enterococcal infections intrinsically resistant to?

Answer 54

all cephalosporins, trimetoprim-sulfa, aminoglycosides