ORAL REVALIDA Flashcards
What is Streptolysin O?
Streptolysin O is a hemolytic toxin produced by Group A beta-hemolytic Streptococcus (S. pyogenes). It is oxygen-labile, meaning it is inactivated by oxygen
What is the difference between Streptolysin O and Streptolysin S?
• Streptolysin O is oxygen-labile, only active in a reduced state, and is antigenic (stimulates ASO antibodies).
•Streptolysin S is oxygen-stable, active in both reduced and oxidized conditions, and is non-antigenic (no antistreptolysin S test).
What are the three types of hemolysis in Streptococcus species?
- Beta-hemolysis – Complete hemolysis (clear zone on blood agar).
- Alpha-hemolysis – Partial hemolysis (greenish discoloration).
- Gamma-hemolysis – No hemolysis.
How do you differentiate Group A from Group B beta-hemolytic streptococci?
• Group A (S. pyogenes): Bacitracin-sensitive, CAMP-negative.
• Group B (S. agalactiae): Bacitracin-resistant, CAMP-positive.
What test differentiates S. pneumoniae from Viridans Streptococcus?
Optochin Test:
• S. pneumoniae: Optochin-sensitive, bile-soluble.
• Viridans Strep: Optochin-resistant, bile-insoluble.
Why is the ASO test important?
The Anti-Streptolysin O (ASO) test detects antibodies against Streptolysin O. It helps diagnose post-streptococcal complications like rheumatic fever and post-streptococcal glomerulonephritis.
What does a high ASO titer indicate?
A recent or past Streptococcus pyogenes infection, which could lead to complications such as rheumatic fever or glomerulonephritis.
What enzymes are produced by Group A Streptococcus?
- DNAse – Breaks down DNA, aids in chromatin breakdown during apoptosis/necrosis.
- Streptokinase – Causes complete hemolysis on blood agar by breaking down blood clots.
What is Anti-Streptolysin O (ASO)?
ASO is a neutralizing antibody produced after a Streptococcus pyogenes infection. It binds to and neutralizes the hemolytic activity of Streptolysin O (SLO).
When does ASO appear in the blood after infection?
ASO appears in serum 1 week to 1 month after a streptococcal infection.
What are the normal values (NV) for ASO titer?
• Children: <150 U/mL
• Adults: <200 U/mL
What is the incubation period for ASO production?
Around 2 weeks after infection. It peaks at 5 weeks.
What is the ASO test used for?
To diagnose post-streptococcal conditions such as:
• Rheumatic fever
• Glomerulonephritis
What is the timeline for ASO antibody levels?
• Rises after 1 to 3 weeks of infection.
• Peaks at 3 to 5 weeks.
• Declines to insignificant levels by 6 months.
• Persistent high levels suggest recurrent or chronic infection.
How does ASO inhibit Streptolysin O?
ASO binds to Streptolysin O and prevents its hemolytic activity
How is ASO titer estimated?
By diluting the patient’s serum in the presence of a constant amount of Streptolysin O until hemolysis is completely prevented.
What does the ASO level depend on?
The amount of Streptolysin O produced by Streptococcus pyogenes in the infected host.
What are the commercially available ASO tests?
- ASO Latex Slide Test – Used for rapid screening of high ASO titers.
- ASO Titration Test – Determines the exact titer of ASO antibody.
What is the principle of the Rapid ASO Latex Agglutination Test?
ASO antibodies in the patient’s serum react with latex particles coated with Streptolysin O antigen, causing visible agglutination.
What type of specimen is required for the ASO test?
Clear, hemolysis-free serum. because the test measures antibodies specifically anti streptolysin O which are present in the serum
How should ASO reagents be stored?
• Keep refrigerated at 2–8°C.
• DO NOT freeze.
• Reagents are stable until the expiration date.
What should ASO latex reagent look like after shaking?
It should be uniform without visible clumping. Slight sedimentation when refrigerated is normal.
When should ASO reagents or controls not be used?
When they show contamination or visible clumping after shaking
How should the serum sample be stored?
• If testing the same day → Keep at 2–8°C.
• If not tested within 7 days → Store at -20°C.
• For longer periods → Must be frozen.
What types of serum should not be used in ASO testing?
Hemolytic or contaminated serum should not be used.
What types of ligands can CRP recognize?
Self ligands (from damaged cells):
• Plasma lipoproteins
• Damaged cell membranes
• Phospholipids
• Small nuclear ribonucleoprotein components
• Apoptotic cells
Extrinsic ligands (pathogens):
• Phospholipids
• Capsular/cell body components of bacteria fungi or parasites
What are positive acute-phase proteins (APPs)?
• C-reactive protein (CRP)
• Serum Amyloid A (SAA)
• Haptoglobin (Hp)
• Ceruloplasmin
• α2-Macroglobulin
• α1-Acid glycoprotein (AGP)
• Fibrinogen
• Complement proteins (C3, C4)
What are negative acute-phase proteins?
These decrease during inflammation. Examples:
• Albumin
• Transferrin
• Transthyretin
• Retinol-binding protein
What does a high CRP level indicate?
It indicates inflammation, which may be due to infection, autoimmune disease, or tissue damage.
Is CRP disease-specific?
No, CRP is a nonspecific marker of inflammation. it is produced in response to a wide range of inflammatory conditions but it doesn’t indicate the specific cause or location of the inflammation
How can CRP help in disease monitoring?
• Tracks disease progression and flares (e.g., autoimmune diseases).
• Helps differentiate between bacterial vs. viral infections (high CRP → bacterial infection).
• Monitors treatment effectiveness and postoperative complications.
Which interleukins regulate CRP production?
• IL-1: Primary inducer of inflammation.
• IL-2: Regulates acute-phase protein production.
CRP vs. ESR
CRP
- rapidly produced
- more sensitive
- more specific
ESR
- delayed
- moderate sensitivity
- less specific
What is the normal value (NV) for CRP?
<10 mg/L
What are the main functions of CRP?
- Anti-infective actions
• Opsonizes particles for phagocytosis
• Activates complement via the classical pathway - Anti-inflammatory actions
• Prevents systemic inflammation
• Aids in neutrophil release from blood vessels
• Prevents white cell adhesion in non-inflamed tissue - Scavenging action
Does CRP bind to normal cell membranes?
No, CRP only binds to cells undergoing apoptosis or necrosis.
What happens when CRP binds to damaged cells?
• Activates complement
• Initiates an inflammatory reaction
• Attracts neutrophils and monocytes to the site
Processes Induced by CRP
- Complement Activation – Enhances immune response by opsonization and cell lysis.
- RAAS Activation – Increases blood pressure and fluid retention, contributing to inflammation.
- Vascular Wall Damage – Inflammatory cells infiltrate, smooth muscle proliferates, increasing atherosclerosis risk.
- Prothrombotic State – activation of completion cascade. Promotes clot formation by increasing thrombin, adhesion molecules, and platelet stickiness.
- Endothelial Dysfunction – Reduces nitric oxide, impairing vasodilation and damaging blood vessel lining or glycocalyx
- Opsonization of Oxidized LDL – easier macrophage uptake, formation of foam cells.
Factors Affecting CRP Levels & its effects
• Gender – Higher in women than men.
• Body Mass – Weight loss decreases CRP.
• Ethnicity – Higher in Black individuals than in White individuals.
• Exercise – Lowers CRP levels.
• Alcohol Consumption – Decreases CRP levels.
what happens in complement activation and RAAS activation
- Complement Activation - Enhances immune response by opsonization and cell lysis.
- RAAS Activation - Increases blood pressure and fluid retention, contributing to inflammation.
what happens in Vascular Wall Damage
Inflammatory cells infiltrate, smooth muscle proliferates, increasing atherosclerosis risk.
what happens in Prothrombotic State
activation of completion cascade.
Promotes clot formation by increasing thrombin, adhesion molecules, and platelet stickiness.
what happens in endothelial dysfunction
Reduces nitric oxide, impairing vasodilation and damaging blood vessel lining or glycocalyx
what happens in Opsonization of Oxidized LDL
easier macrophage uptake, formation of foam cells.
Methods for CRP Detection
• ELISA
• Immunoturbidimetry
• Rapid Immunodiffusion
• Visual Agglutination
Clinical Importance of CRP
- Elevated CRP
- Mild CRP Elevation
- Normalization of CRP
- Transplant Cases
- Cerebral Vein Thrombosis
- Giant Cell Arteritis
- Pancreatitis
What are the methods for CRP detection?
• ELISA
• Immunoturbidimetry
• Rapid Immunodiffusion
• Visual Agglutination
What conditions are associated with elevated CRP levels?
Elevated CRP is seen in osteoarthritis, coronary events, and prothrombotic states.
What conditions are associated with mild CRP elevation?
Mild CRP elevation is found in SLE, scleroderma, Sjogren’s syndrome, and dermatomyositis/polymyositis.
How is CRP used to assess antibiotic therapy response?
Normalization are a helpful tool in determining response to antibiotic therapy because it indicates a positive response to antibiotic therapy.
What is the significance of CRP in transplant cases?
- Elevated CRP is seen in kidney and heart transplants, with highly increased levels in graft-versus-host disease (GVHD).
- Changes in levels are not organ specific, like other inflammatory conditions
How does CRP relate to cerebral vein thrombosis?
High CRP levels are linked to a poor short-term prognosis in cerebral vein thrombosis.
How is CRP used in diagnosing giant cell arteritis?
A CRP level >2.45 mg/dL along with thrombocytosis (pc >400,00/uL) predicts a positive temporal artery biopsy.
What is the CRP pattern in pancreatitis?
CRP peaks 3 days post-onset, and levels >150 mg/L suggest severe disease.
What is high-sensitivity CRP (hs-CRP)?
hs-CRP is a more sensitive marker than CRP, especially for detecting cardiovascular injury.
What is the normal range for hs-CRP?
The normal range is <0.3 mg/dL
What are the uses of hs-CRP?
• Cardiovascular risk assessment (predicts CVD, stroke, peripheral vascular disease).
• Identifies risk for hypotension.
