ASO
(Ani Streptolysin O)
Dr. M. Izad
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)
Streptococcal Antibody Test
Streptolysin O: An exotoxin which is
sensitive to oxygen.
General pattern of antibody response to
group A streptococcal extracellular antigen
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
0.6
0.4
0.3
--
--
SO
0.5
0.5
0.5
0.5
--
0.5
20 min in room temperature
Red
blood
cells
0.5
0.5
0.5
0.5
0.5
0.5
Titer
(Todd)
125
166
250
333
No lysis
lysis
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.
Interpretation of the result
Different
factors such as age ,previous
infection, immune system status & society affect
the ASO interpretation
Titer in adults: 250 unit
300-1500
Acute rheumatic fever (85%)
Todd
Acute post streptococcal glomerulonephritis
(ADNaseB)
VDRL
(Veneral Disease Research Laboratory)
&
RPR
(Rapid Plasma Reagin)
Syphilis
(Treponema Pallidum)
• Primary syphilis
•Secondary syphilis
•Latent syphilis
•Tertiary/ late latent syphilis
Laboratory diagnosis
Microscopic Tests
Dark field
Immunoflurescense
Serologic Tests
Screening
non-Treponema
tests
(non-
specific/VDRL, RPR)
Confirming Treponema tests (specific/FTAabs)
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
False positive & False negative
False positive:
Intravenous drug users (10% FP)
Pregnancy
Autoimmune disease (Rheumatoid
lupus)
Aged individuals
Chronic infection (leprosy)
Arthritis,
False negative:
Prozone phenomena (FN /1-2% secondary syphilis)
Latent syphilis
CRP
C-Reactive Protein
Acute Phase Protein
Passive agglutination
the increase of CRP serum
concentrations observed in
• Microbial infections
• Acute rheumatic fever
• Acute myocardial infarction
• Rheumatoid Arthritis
• Cancer
CRP
•
Severity of the disease & effectiveness of
therapy
•
False positive:
– Corticosteroids
– Prozone
•
False positive:
– Old serum