Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Microbiology > Streptococcus > Flashcards

Streptococcus Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
0
Q

Strep and Staph, which one clusters, which one is in chains?

A

Strep in chains

Staph in clusters

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
1
Q

What does pyogenic mean?

A

Pus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Streptococcus pyogenes

A

Pharyngitis and skin/soft tissue infections

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

viridans (means green) streptococci

A

common cause of infective endocarditis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

streptococcus pneumoniae

A

pneumonia, upper respiratory infections, meningitis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

enterococcus faecalis and enterococcus faecium

A

nosocomial infections

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Streptococcus gram stain and culture?

A

Gram positive cocci (spherical)

Arranged in chains or pairs (divides in one plane)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

streptococcus pneumoniae gram stain and culture

A

diplococci but can be in chains

lancet-shaped

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

catalase test to distinguish what?

A

Strep is catalase negative

Staph is catalase positive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What do you look at to distinguish between strep types?

A

Hemolysis patterns

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Beta strep/hemolysis

A

Clear zone from complete lysis of RBCs because of production of hemolysins (streptolysin O and streptolysin S)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

alpha strep/hemolysis

A

Green zone due to incomplete lysis of RBCs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Gamma strep/hemolysis

A

No hemolysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Strep pyogenes hemolysis pattern?

A

Beta

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Strep pneumoniae hemolysis?

A

alpha

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How to distinguish between strep pneumoniae and viridans strep?

A

Strep pneumoniae is bile soluble and inhibited by optochin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

viridans strep hemolysis?

A

alpha, green!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Besides hemolysis patterns, what is another way to classify strep?

A

Lancefield classification A-V

Based on antigenic differences in C carbohydrate of cell wall

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Group A strep is sensitive to bacitracin, whats an example?

A

strep pyogenes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Group B is resistant to bacitracin and hydrolyzes hippurate. Ex?

A

Strep agalactiae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Group D strep hyrolyzes esculin in the presence of bile producing a black pigment. Examples?

A

Enterococcus grows in high salt

streptococcus bovis does not grow in high salt

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the most important virulence factor for strep pyogenes? What does it do? Is there an antibody for it?

A

M protein
inhibits opsonization: blocks phagocytosis
Yes but its only strain specific

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Does strep pyogenes have a capsule? Can antibodies be made against it?

A

Yes, it is an anti-phagocytic capsule
Antibodies can’t be made against it because the capsule is made of hyaluronic acid which is a normal component of the human body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

2 enzymes made by group A strep (strep pyogenes)

A 
streptokinase - activates plasminogen to form plasmin, which dissolves fibrin in clots
streptolysin O (anti-streptolysin O antibody can be used to diagnose recent group A strep infections which can be important for diagnosing rheumatic fever)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is strep pyogenes erythrogenic toxin? What is it produced by?

A

causes the rash of scarlet fever
functions as superantigen (polyclonal stimulation of subset of T cells to produce cytokines)
produced only by strains that carry a lysogenic phage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

There are toxins involved with specific clinical presentations. strep pyrogenic exotoxin A (superantigen) ?

A

strep toxic shock syndrome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

There are some toxins involved with specific clinical presentations. Strep pyrogenic exotoxin B?

A

necrotizing fasciitis

27
Q

Strep pyogenes is normal flora… where?

A

skin

28
Q

Strep pyogenes can cause 3 types of disease:

A
  1. pyogenic - inflamm produced locally at site where organisms are present (pharyngitis, cellulitis)
  2. toxigenic - exotoxin production can cause systemic symptoms at sites where organism is not present (scarlet fever, strep toxic shock syndrome)
  3. immunologic - inflamm at sites where there are no organisms (rheumatic fever, acute glomerulonephritis)
29
Q

strep pyogenes is the most common bacterial cause of

A

sore throat, strep throat

30
Q

throat swab of someone with strep pyogenes doesn’t distinguish between normal flora and infection, why?

A

Some people are carriers but doesn’t mean they are sick

31
Q

erysipelas?

A

strep pyogenes infection involving the skin

32
Q

cellulitis?

A

strep pyogenes infection involving the skin and superficial fascia

33
Q

necrotizing fasciitis?

A

strep pyogenes infection affecting the fascia

34
Q

scarlet fever is caused by what and looks like what?

A

strep pyogenes toxin mediated disease (erythrogenic toxin)

diffuse sand paper rash and sunburn look

35
Q

how do you distinguish strep and staph toxic shock?

A

strep toxic shock usually has obvious site of soft tissue infection and positive blood cultures

36
Q

What are two presentations of inflammation (at different sites than the original microorganisms) created by a post-strep pyogenes infection?

A
  1. acute glomerulonephritis - immune complex deposition
  2. acute rheumatic fever - autoimmune disease caused by cross-reaction of strep M protein antibodies with human antigens in heart, brain, joints
37
Q

acute glomerulonephritis occurs after what? Preventative treatment?

A

Occurs after skin/soft tissue infection or pharyngitis
No preventative treatment
smoky or rust colored urine

38
Q

Acute rheumatic fever occurs after what? What can it cause? Preventative treatment?

A

Pharyngitis, not skin/soft tissue infections
Can cause mitral and aortic valve damage
Yes, antibiotics within 9 days of onset of pharyngitis

39
Q

All group A strep are sensitive to what antibiotic?

A

penicillin G

40
Q

What is the most important virulence factor for strep pneumoniae?

A

polysaccharide capsule

it is anti-phagocytic like all capsules

41
Q

how many different capsular types of strep pneumoniae?

A

> 90

42
Q

What do the antibodies against strep pneumoniae do?

A

opsonize them

43
Q

What is the Quellung reaction?

A

anti-capsular antibody causes the capsule to swell

44
Q

What percent of adults and children have strep pneumoniae as normal flora in their oropharynx?

A

5-10% adults

20-40% children

45
Q

What two things can strep pneumoniae also cause?

A

bacteremia and meningitis

46
Q

How often do people with strep pneumoniae also get bacteremia?

A

10-20% of cases

47
Q

What does the sputum of a person with strep pneumoniae look like?

A

purulent - bloody

48
Q

What do people who have had a splenectomy, hyposplenism, and sickle cell disease have in common?

A

At risk for invasive pneumococcal disease

49
Q

What is a rapid test for strep pneumoniae

A

Latex agglutination test of CSF

50
Q

When would you use a strep pneumoniae urinary test, what is it looking for?

A

When you suspect bacteremia
C polysaccharide from cell wall
Its not as sensitive for mild infections

51
Q

How many strains of strep pneumoniae are not fully penicillin susceptible? Why?

A

5%
Altered penicillin binding protein with decreased binding affinity for penicillin (not inhibited by beta lactamase inhibitor)

52
Q

What are the two vaccines available for strep pneumoniae?

A
  1. polysaccharide vaccine for adults and older children (23 valent)
  2. conjugate vaccine for young children (13 valent, conjugated to a carrier protein diphtheria toxoid which stimulates a helper T cell response)
53
Q

Group D streptococcus that grows in high salt

A

enterococcus

54
Q

Enterococcus is normal flora where?

A

colon

55
Q

2 main enterococcus pathogens?

A

E. faecalis - more common, usually not vancomycin resistant

E. faecium - more likely to be resistant to vancomycin

56
Q

vancomycin resistant enterococcus cause what?

A

nosocomial infections

57
Q

how does enterococcus become resistant to vancomycin?

A

altered cell well oligopeptide with low affinity for vancomycin so there would be decreased inhibition of peptidoglycan synthesis

58
Q

vancomycin resistant enterococcus is acquired in the hospital. Where does it hang out?

A

In colons of patients and is transferred to other patients by healthcare workers

59
Q

are vancomycin resistant enterococcus infections usually E. faecium or E. faecalis?

A

E. faecium

60
Q

Most positive VRE cultures represent what?

A

Colonization

61
Q

Treatment: penicillin sensitive, penicillin resistant, vancomycin resistant?

A

penicillin-sensitive: penicillin + aminoglycoside (gentamicin) for synergy
penicillin-resistant: vancomycin
VRE: linezolid or daptom

62
Q

what is a group D streptococcus that doesn’t grow in high salt?

A

streptococcus bovis

63
Q

there is an association with strep bovis bacteremia and endocarditis with what?

A

colon carcinoma

64
Q

What is a common cause of infective endocarditis?

A 
viridans streptococcus
(endocarditis presents several weeks after a dental procedure)
65
Q

What is strep agalactiae? what group?

A

Group B
Colonizes genital tract of some women
Causes neonatal meningitis and sepsis and postpartum endometritis

66
Q

Prevention/treatment of strep agalactiae?

A

Screen with vaginal/rectal cultures at 35-37 weeks of pregnancy
Rapid antigen test
If test is positive, treat with penicillin G at delivery

Microbiology (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions