Streptococci and Enterococci Flashcards Preview

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Flashcards in Streptococci and Enterococci Deck (54)
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1

What are 2 key features of Streptococci?

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

2

________ are aerobic while _____________ are anaerobic

staph (aero)
strep (anaero)

3

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

catalase positive - O2 bubbles up

4

What are the 3 hemolytic properties of strep?

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

5

What is the important strep species of Group A?

streptococcus pyogenes

6

What is the important strep species of Group B?

streptococcus agalactiae

7

What kind of infections are associated with S. pyogenes?

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

8

What are 7 clinical manifestations of strep pyogenes infection?

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

9

What two bacteria can cause toxic shock?

staph and strep (group A)

10

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

staph = TSST-1
strep = SPE

11

What patient population do you see puerperal sepsis?

women following delivery

(bacteria from genital tract or obstetric personnel invade upper genital tract)

12

What are dangerous sequelae after strep?

Rheumatic fever (1-5 weeks after)

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

13

Why can rheumatic fever be dangerous?

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

14

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

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

15

What are the 7 S. pyogenes virulence factors?

Capsular polysaccharide
lipoteichoic acid
hemolysins
streptokinase
hyaluronidase
nuclease
C5a peptidase

16

What are the 2 hemolysins of S. pyogenes?

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

17

What is SPE?

streptococcal pyrogenic exotoxins

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

18

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

M protein

19

What does the M protein do?

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

20

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

streptolysins
streptokinase

21

True or false: there are antibiotic resistant strep pyogenes?

FALSE

22

What drugs do you use to treat s. pyogenes?

penicillin/ampicillin/amoxacillin

cephalosporins

erythromycin (for pen allergic patient)

23

What does strep agalactiae cause?

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

24

Is strep agalactiae normal on the body anywhere?

throat, vaginal and GI tract

25

How can baby get GBS (group b strep)?

normal maternal colonization of vagina or rectum exposes baby at delivery

leads to meningitis, bacteremia, pneumoniae

26

How do you prevent babies from getting GBS at delivery?

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

27

How do you treat GBS?

penicillin/ampicillin

gentamicin to enhance killing

clindamycin for pen allergic

28

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

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

29

How do you diagnose GBS?

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

30

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

FALSE; always do a back up culture

31

What are Viridans Streptococci?

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

32

What are the 5 groups of viridans strep?

- sanguis
- mitis
- mutans
- salivarius
- bovis

33

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

non-enterococcal group D strep

bacteremia, meningits, endocarditis

34

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

carcinoma of colon

35

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

strep milleri

36

Where are strep milleri infections usually found?

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

37

Where is strep milleri usually found?

mouth, oropharynx, GI tract, vagina

38

Where is strep pneumoniae usually found?

upper resp tract

39

What can strep pneumo cause?

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

40

For which bug is a polysaccharide capsule important virulence factor?

strep pneumoniae

41

Name the 5 virulence factors of strep pneumoniae

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

42

What does sIgA protease do?

prevent IgA mediated binding of pneumococcal cells to mucus

43

What does teichoic acid/peptidoglycan do?

activates complement by alt pathway --> mediates inflammation

44

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

s. pneumoniae

45

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

s. pneumoniae

46

What does s. pneumoniae look like?

gram+
lancet shaped cocci
diplococci

47

What does s. pneumoniae look like on blood agar?

dimes, alpha hemolytic

48

What inhibits s. pneumoniae growth in the lab?

optochin

49

How do you decide how to treat strep pneumococcal infections?

look at MIC for susceptibility

50

What 3 drugs can you give for susceptible pneumococcal infections?

penicillin
cefotaxime
ceftriaxone

51

What are some characteristics of enteroccus?

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

52

What are the 2 classes of entercoccus virulence factors?

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

53

true or false: there are some vancomycin resistant enterococci

TRUE (E. faecium)

Van A - plasmid mediated
Van B - chromosomal
Van C - intrinsic

Makes YELLOW colonies

54

What are enterococcal infections intrinsically resistant to?

all cephalosporins, trimetoprim-sulfa, aminoglycosides