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ASO (Ani Streptolysin O)
Dr. M. Izad
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ASO A diagnosis test for:
Acute rheumatic fever (2-3% Pharyngitis-Tonsilitis) ( Antigeng M) Rheumatic heart disease Acute post streptococcal glomerulonephritis (2-5% Chronic) (Streptokinase)
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Streptococcal Antibody Test
Streptolysin O: An exotoxin which is sensitive to oxygen.
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General pattern of antibody response to group A streptococcal extracellular antigen
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ASO an enzyme inhibition test
Tube NO. 1 2 3 4 Red cells control SO control ASO Buffer 0.2 0.4 0.6 0.7 1.5 1 (ml) Serum 0.8 0.3 -- SO 0.5 20 min in room temperature Red blood cells Titer (Todd) 125 166 250 333 No lysis lysis
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Todd Unit: concentration of ASO which neutralize completely 2
Todd Unit: concentration of ASO which neutralize completely 2.5 minimum hemolytic dose of SO. minimum hemolytic dose of SO :the smallest amount of SO that produces complete lysis of 0.5 ml of 5% red blood cells at 37°c in 1h. The unit in which the results of testing for antistreptolysin O (ASO) are expressed. It denotes the reciprocal of the highest dilution of test serum at which there continues to be neutralization of a standard preparation of the streptococcal enzyme streptolysin O.
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Interpretation of the result
Different factors such as age ,previous infection, immune system status & society affect the ASO interpretation Titer in adults: 250 unit Acute rheumatic fever (85%) Todd Acute post streptococcal glomerulonephritis (ADNaseB)
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VDRL (Veneral Disease Research Laboratory) & RPR (Rapid Plasma Reagin)
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Syphilis (Treponema Pallidum)
Primary syphilis Secondary syphilis Latent syphilis Tertiary/ late latent syphilis
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Laboratory diagnosis Microscopic Tests Serologic Tests Dark field
Immunoflurescense Serologic Tests Screening non-Treponema tests (non-specific/VDRL, RPR) Confirming Treponema tests (specific/FTAabs)
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Interpretation of the result
Flucculation (negative/ weak positive/ positive) Titration (1/8, 1/16, 1/32) Primary syphilis: 30% Neg (repeat after 1w/ 1&3mo) Titration is used for confirming of threapy Secondary syphilis: 100% psitive &over 1/16 Late latent syphilis: 20% Neg
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False positive & False negative
Intravenous drug users (10% FP) Pregnancy Autoimmune disease (Rheumatoid Arthritis, lupus) Aged individuals Chronic infection (leprosy) False negative: Prozone phenomena (FN /1-2% secondary syphilis) Latent syphilis
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CRP C-Reactive Protein
Acute Phase Protein Passive agglutination
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the increase of CRP serum concentrations observed in
Microbial infections Acute rheumatic fever Acute myocardial infarction Rheumatoid Arthritis Cancer
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CRP Severity of the disease & effectiveness of therapy False positive:
Corticosteroids Prozone Old serum
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