The Serology of Streptococcal Disease

Question 1

Acute infections associated with Group A Streptococci

Answer 1

1. Pharyngitis
2. Skin infections (impetigo)
3. Scarlet fever
4. Others

Question 2

Group A Strep:

• gram stain?
• hemolysis?

Answer 2

• GPC

- Beta hemolysis on blood agar

Question 3

What is a clinical syndrome not associated with the presence of the organism in the body and immune-mediated, due to immune response to recent or past Group A strep infection?

Answer 3

Post-streptococcal Disease

Question 4

Two examples of post-streptococcal disease

Answer 4

1. Rheumatic Fever

2. Post-streptococcal Glomerulonephritis

Question 5

What is caused by a cross-reaction of anti-group A streptococcal antibodies an certain heart tissues?

Answer 5

Rheumatic Fever

Question 6

What is caused by Group A streptococcal antigen/antibody complexes getting trapped in the glomerular basement membrane and destroying it?

Answer 6

Post-Streptococcal Glomerulonephritis

Question 7

What re two reasons we use serology to aid in diagnosis of post-streptococcal syndromes?

Answer 7

1. syndromes not associated with presence of organism in the body (organism not present to be isolated)
2. Immune-mediated, due to immune response to recent or past Group A strep infection (antibodies presist as marker of infection

Question 8

Basic principles of Strep Disease Serology:

- Poor immune response to antigens associated with the ______ _____ ______ and Group A carbohydrate

Answer 8

bacterial cell body

Question 9

Basic priniples of Strep Disease Serology:

- Antibodies are produced against Group A streptococcal __________.

Answer 9

exoenzymes

Question 10

Name the 5 Exoenzymes of Group A Streptococci

Answer 10

1. DNase
2. NADase
3. Streptolysin O
4. Streptokinase
5. Hyaluronidase

Question 11

Two Assays used for Streptococcal Serology?

Answer 11

Antistreptolysin O

Streptozyme

Question 12

Antistreptolysin O:

- serologic principle

Answer 12

Use nephelometry to measure reactivity in a passive agglutination (quantitative)
- add patients serum (antibodies) to antigen coated carrier particles (coated with streptolysin O) If binding of Ag/Ab then agglutination

Question 13

Antistreptolysin O:

- describe antigen and antibody detected

Answer 13

Antigen: streptolysin O
Antibody: antistreptolysin O

Question 14

Antistreptolysin O:

- How does sensitivity of test relate to the kind of streptococcal infection

Answer 14

• Produced in 100% of group A strep pharyngitis
• Not produced in some group A skin infections
• May be produced in Group C or G beta hemolytic strep infections

Question 15

Antistreptolysin O:

- Reference range for normal, healthy individuals (children vs adults)

Answer 15

Preschool children: < 100 IU/ml

Older Children/Adults: < 200 IU/ml

Question 16

Antistreptolysin O:

- results expected in infected individuals

Answer 16

Agglutination

Question 17

Strep Enzyme Antibody - Qualitative Test (Streptozyme):

- list all antibodies detected

Answer 17

antibodies against any of the 5 enzymes (Streptolysin O, Streptokinase, Hyaluronidsase, DNase, NADase)

Question 18

Strep Enzyme Antibody - Qualitative Test (Streptozyme):

- Name serologic principle of test

Answer 18

Passive Hemagglutination

Question 19

Strep Enzyme Antibody - Qualitative Test (Streptozyme):

- Describe antigens used and the carrier particle

Answer 19

Antigens: extract of ALL five Group A streptococcal antigens
Carrier particle: erythrocyte

Question 20

Strep Enzyme Antibody - Qualitative Test (Streptozyme):

- How do results correlate with results of ASO?

Answer 20

Detects 5 kinds of antibodies where ASO detects Streptolysin O antibodies

Question 21

Strep Enzyme Antibody - Qualitative Test (Streptozyme):

- Will all ASO-pos samples also test pos by streptozyme?

Answer 21

Yes

Question 22

Strep Enzyme Antibody - Qualitative Test (Streptozyme):

- Will all ASO-neg samples also test neg by streptozyme?

Answer 22

No because ASO only detects Streptolysin O and Streptozyme can be positive for another enzyme.

Question 23

C-Reactive Protein (CRP) Test:

- Define

Answer 23

A PROTEIN found when inflammation is present (marker of inflammation)

Question 24

C-Reactive Protein (CRP) Test:

- Diseases in which CRP test is usually positive

Answer 24

Not a marker of any one disease but often tested in suspected bacterial infections because these produce much inflammation

Question 25

C-Reactive Protein (CRP) Test:

- Does a positive CRP test confirm an infection with Group A strep?

Answer 25

No not a conformation

Question 26

C-Reactive Protein (CRP) Test:

- testing mechanisms sometimes used in CRP determinations

Answer 26

passive agglutination
precipitation
Etc.

Question 27

C-Reactive Protein (CRP) Test:

- result that is expected in a normal, healthy individual

Answer 27

Normal CRP

Question 28

Procalcitonin Assay:

- chemical composition and biologic function

Answer 28

peptide precursor of the hormone calcitonin produced by C cells in the thyroid and cells in the lungs and intestine

Question 29

Procalcitonin Assay:

- when do levels increase rapidly

Answer 29

in bacterial sepsis

Question 30

Procalcitonin Assay:

- Gram negative v.s. Gram positive and fungal

Answer 30

Levels rise faster and higher in Gram Negative sepsis then Gram positive or fungal sepsis

Question 31

Procalcitonin Assay:

- list 4 conditions when levels may be increased?

Answer 31

• autoimmune disease
• organ transplant rejection
• burn injuries
• newborns during first days after delivery

Question 32

Procalcitonin Assay:

- Describe normal levels in healthy humans

Answer 32

Very low levels in healthy humans (undetectable?)

Question 33

Procalcitonin Assay:

- known components used in the test system and unknown components detected in patients sample

Answer 33

PCT Testing is EIA test on Vidas instrument

- Anti-PCT anitbodies (known) bind PCT (unknown antigen)