Anti-Streptolysin O (ASO) Flashcards
Streptolysin O is a hemolytic factor produced by most strains of?
Group A beta-hemolytic streptococci (S. pyogenes)
what are streptococci
are gram positive cocci in chain, non-motile, facultative anaerobes
Toxins and Enzymes Produced by S. pyogenes
toxin: streptolysin O and streptolysin S
enzymes: DNAse and streptokinase
oxygen-labile (sensitive to oxygen)
streptolysin o
oxygen-stable
Streptolysin S
Hemolytic Streptococci with no hemolysis
Gamma Hemolvtic Streptococcus
Gamma Hemolvtic Streptococcus are commonly seen with?
enterococcus on blood agar plates
Hemolytic Streptococci - Clear complete hemolysis on blood agar plates
Beta Hemolytic
Beta Hemolytic Strep is divided into two groups
-Group A (S. pyogenes)
-Group B (S. agalactiae)
Group A (S. pyogenes) in bacitracin & CAMP test
Bacitracin-sensitive, CAMP-negative
Group B (S. agalactiae) in bacitracin & CAMP test
Bacitracin-resistant, CAMP-positive
Differentiates S. pyogenes from S. agalactiae
CAMP & Bacitracin Test
Standard method for Group B Strep identification
Lancefield Precipitation Test
Hemolytic Streptococci - Green with partial hemolysis
Alpha Hemolytic
Alpha Hemolytic is differentiated through what test
Optochin Test
alpha hemolytic is divided into 2 groups
- S. pneumoniae
- T. viridans
differentiate s.pneumoniae and t.viridans
• S. pneumoniae: Optochin-sensitive, bile-soluble
• T. viridans: Optochin-resistant, bile-insoluble
Streptolysin O vs. Streptolysin S
Streptolysin O:
• Active only in reduced state
• Antigenic (produces ASO antibodies)
Streptolysin S:
• Active in both reduced and oxidized
• Non-antigenic (no anti-Strep S test)
Specifies on the chromatin breakdown during apoptosis/necrosis
DNAse
Causes complete hemolysis of blood agar; breaks down chromatin
Streptokinase
It is a specific neutralizing antibody produced after infection with these organisms
ANTI-STREPTOLYSIN O
when does anti strep o appear
appears in serum from 1 week - 1 month after onset of a streptococcal infection.
what does anti strep o do
It combines and neutralizes the hemolytic activity of streptolysin O
Normal Values (NV) for ASO
• Children: <150 UL/mL
• Adults: <200 UL/mL
ASO Incubation Period
• 2 weeks: Start of signs and symptoms
• 5 weeks: Peak levels
Used to confirm false negatives
DNAse Test
Determines an organism’s ability to hydrolyze DNA for carbon and energy
DNAse Test
Uses of ASO Test
Diagnoses conditions from streptococcal infections, especially:
• Rheumatic fever
• Glomerulonephritis
ASO Antibody: 1-3 weeks
Antibodies begin to appear
ASO Antibody: 3-5 weeks
Peak levels
ASO Antibody: Up to 6 months
Antibody levels decline to insignificant levels
what does persistent high titer indicate
recurrent or chronic infection
antibody that appears in patients serum days after infection
Antibodies (IgG)
ASO test principles: reaction
ASO binds to Streptolysin O (SLO) and inhibits hemolysis.
how is the amount of ASO estimated
Patient serum is diluted until hemolysis is completely inhibited.
Screens for significant ASO titer increase.
ASO Latex Slide Test
Determines ASO antibody titer.
ASO titration test
principle of Rapid ASO Latex Agglutination Test
Visible agglutination occurs when ASO antibodies in serum react with latex particles coated with SLO antigen.
specimen used for Rapid ASO Latex Agglutination Test
Clear, hemolysis-free serum.
storage temp for aso reagents and specimens
2-8C
is slight sedimentation after refrigeration normal
yes
Specimen Type
Fresh serum from centrifuged clotted blood.
Short-Term Storage
2 - 8°C for up to 7 days.
Long-Term Storage
• -20°C if stored for 3 months or more.
