Brainscape's Knowledge GenomeTM

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


See full index

immuno/micro exam 2 > Streptococci > Flashcards

Streptococci Flashcards

1
Q

Overview of Streptococci

A 
A) Gram positive cocci
B) seen as Chains or diplococci
C) Non-spore forming
D) Facultative anaerobes
----Grow with/without oxygen
E) Catalase negative
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is a Lancefield group?

A

Serological classification based on major cell-wall carbohydrate antigens

Groups lettered A-U, but some streptococci cannot be assigned to any group

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

how are streptococci species classified?

A

Metabolic reactions in culture media

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

what does culturing Strep in a blood agar medium show us?

A

Hemolysis pattern

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

what are the Hemolysis patterns?

A 
a = partial hemolysis and green discoloration of hemoglobin
b = clear zone of complete hemolysis
g = no zone of clearing
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Group A Streptococcal Diseases

A 
A) Acute pharyngitis
B) Pyoderma (skin/soft tissues)
C) Group A streptococcal pneumonia
D) Necrotizing fasciitis 
E) food-born outbreaks
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is another name for group A strep? (GAS)

A

S. pyogenes

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

what illnesses are S. pyogens (GAS) responsible for?

A 
Streptococcal acute pharyngitis (strep throat)
Scarlet fever (strep throat + red skin rash)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Acute Rheumatic Fever (ARF)

A

A) Fairly common until mid-20th century
B) Nonsuppurative sequelae (non-pus forming secondary results)
C) Pharynx is the only site of infection that is followed by ARF
D) Completely prevented by treating strep throat with full course of penicillin

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

Acute Post-Streptococcal Glomerulonephritis (APSGN)

A

A) Active inflammation in the glomeruli of the kidneys
B) Urine smoky due to proteins, leukocytes and erythrocytes, renal failure
C) Caused by only a few types of GAS

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

Group A Infections – Encounter

A

A) Live on skin and mucous membranes

B) Person to person transmission

  • Infected respiratory droplets
  • Hand-to-hand-to-mouth
  • Food
  • Skin/wound infections
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

can group a infections penetrate the skin?

A

NO- must find cut/lesion/bite/wound to enter thru

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

group A Bacteria bind to epithelial cells using

A

adhesins

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

Adhesins

A

Lipoteichoic acid (LTA)

  • Cell wall of Gram positive bacteria
  • Makes streptococci sticky
  • Binds to fibronectin on epithelial cell surfaces (coats oropharynx cells)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Besides Lipoteichoic acid, what are the other 2 adhesins used by group A strep?

A

Protein F – high affinity fibronectin binding protein

M protein – keratinocytes (outer skin) adhesin

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

how does Group A streptococci spread?

A

Depends on how infection was acquired

A) On skin or mucous membranes, usually remains localized
B) Deeper tissue infections- rapid spread

17
Q

Streptokinase

A

binds to, and activates host plasminogen

A) plasminogen breaks down blood clots

18
Q

how does streptococci avoid phagocytosis?

A

1) M protein – rod-shaped molecule
Most important antiphagocytic factor
2) Central to pathogenesis and required for virulence

3) Hyaluronic acid capsule – mucoid capsule
4) C5a Peptidase – inactivates phagocyte chemotaxin

19
Q

Hyaluronic Acid Capsule

A

Makes strep “slippery”, interfering with phagocyte attachment

20
Q

Streptococcal Pyrogenic Exotoxins (SPEs)

A

1) GAS invokes intense inflammatory response in tissues
2) Superantigens activate macrophages and cause T cells to release of cytokines
- three types- SpeA, SpeB, SpeC

21
Q

what is responsible for the red rash of scarlet fever

A

Superantigens (SPEs)

22
Q

which superantigen causes streptococcal shock syndrome?

A

mainly SpeA

23
Q

Group B Streptococci (GBS)

A

A) Inhabit lower GI and female genital tracts
B) cause cellulitis, arthritis, and meningitis in adults with chronic diseases
C) Polysaccharide capsule that is antigenic
–Unlike hyaluronic acid capsule of GAS

24
Q

Other b-hemolytic Streptococci

A

1) Mainly Groups C, G, and F

2) Implicated in AGN but not ARF

25
Q

Group D Streptococci

A

A) a- or g-hemolytic
B) Enterococci and nonenterococci
C) Normal flora of GI and genitourinary tracts
Low virulence
—usually accompany other bacterial infections

26
Q

Enterococci

A

A) “World’s Toughest Pathogenic Bacteria”
B) Antibiotic synergism required for effective killing

Vancomycin resistant enterococci (VREs)
A) low virulence, but UNTREATABLE

27
Q

Nonenterococcal Group D Streptococci

A

A) S. bovis – most common for human disease
B) Subacute bacterial endocarditis
C) Does not grow in high salt
D) Most strains are killed by penicillin

28
Q

Viridans Streptococci

A

1) a-hemolytic
2) oropharyngeal flora- low virulence
3) Most common cause of subacute bacterial endocarditis
4) Produce dextrans- Adherence

29
Q

Viridans Streptococci – “mutans” group

A

1) Responsible for dental caries
2) Surface proteins bind salivary glycoproteins on teeth (pellicle)
3) Ferment sugar to lactic acid (demineralizes enamel)

immuno/micro exam 2 (7 decks)

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