For MBBS students

1. CRP & ASO
Dr.P.B.PRAVEENKUMAR
FIRST YEAR POST GRADUATE
DEPARTMENT OF MICROBIOLOGY
THANJAVUR MEDICAL COLLEGE

2. HOW TO APPROACH THIS PRACTICAL
EXERCISE IN EXAM????
• AIM
• PRINCIPLE
• PROCEDURE
• INTERPRETATION

3. C-Reactive protein (CRP)
AIM: This test is used for the qualitative and
semiquantitative in-vitro determination of
inflammatory diseases.

4. PRINCIPLE
RAPID LATEX SLIDE AGGLUTINATION TEST:
Uniform latex particles are coated with anti-
human CRP. The specimen containing CRP, on
mixing with latex Reagent agglutinates,
showing the positive test result. If CRP is
absent there will be no agglutination,
indicating a negative test result.

5. PROCEDURE
QUALITATIVE METHOD:
*Bring the reagents and samples to room temperature
*Put three circles in slide for PC,NC & Test.
*Add 25 microlitres of PC,NC & Test in corresponding
circles.
*Add 25 microlitres of CRP latex reagent to all three
circles.
*Spread it over the circle using separate sticks for each
sample.
*Rock the slide to and fro gently for two minutes(Not
beyond 2 minutes) & See for agglutination.

6. INTERPRETATION OF QUALITATIVE
TEST
*Agglutination within two minutes – CRP
POSITIVE
*No agglutination / smooth suspension – CRP
NEGATIVE

7. PROCEDURE (cont.)
SEMIQUANTITATIVE METHOD:
*Dilute the specimen serially in the ratio of 1:2,
1:4, 1:8, 1:16, 1:32, 1:64 using normal saline.
*Add one drop of latex reagent in each of these
circle. Mix well with separate applicator stick.
*Rock the slide gently to and fro for two minutes
and examine for agglutination.

8. INTERPRETATION (cont.) OF
SEMIQUANTITATIVE TEST
Concentration of CRP (mg/dl) =
Sensitivity (0.6 mg/dl) * Titre (Highest dilution)
For example: Agglutination stopped in 1:32 titre
means CRP Concentration = 0.6*32 19.2
mg/dl

9. Anti streptolysin O (ASO)
AIM: This test is used for the qualitative and
semi quantitative in-vitro determination of
ASO in patient serum.

10. PRINCIPLE
LATEX SLIDE AGGLUTINATION TEST: The ASO
latex is a slide agglutination test for the
qualitative and semi quantitative detection of
anti-streptolysin O (ASO) in human serum.
Latex particles coated with streptolysin O
(SLO) are agglutinated when mixed with
samples containing ASO.

11. PROCEDURE
QUALITATIVE METHOD:
*Bring the reagents and samples to room temperature
*Put three circles in slide for PC,NC & Test.
*Add 50 microlitres of PC,NC & Test in corresponding
circles.
*Add 50 microlitres of ASO latex reagent to all three
circles.
*Spread it over the circle using separate sticks for each
sample.
*Rock the slide to and fro gently for two minutes(Not
beyond 2 minutes) & See for agglutination.

12. INTERPRETATION OF QUALITATIVE
TEST
*Agglutination within two minutes – ASO
POSITIVE (INDICATES ASO TITRE EQUAL /
GREATER THAN 200 IU/ML)
*No agglutination / smooth suspension – ASO
NEGATIVE

13. PROCEDURE (cont.)
SEMIQUANTITATIVE METHOD:
*Dilute the specimen serially in the ratio of 1:2,
1:4, 1:8, 1:16, 1:32, 1:64 using normal saline.
*Add one drop of ASO latex reagent in each of
these circle. Mix well with separate applicator
stick.
*Rock the slide gently to and fro for two minutes
and examine for agglutination.

14. INTERPRETATION (cont.) OF
SEMIQUANTITATIVE TEST
Concentration of ASO (IU/ml) =
200 * ASO titre (Highest dilution)
For example: Agglutination stopped in 1:16 titre
means ASO Concentration = 200 * 16

15. THANK YOU