WIDAL AND WEIL FELIX TEST MBBS.pptx

For MBBS students

1. WIDAL AND WEIL FELIX TEST Dr.P.B.PRAVEENKUMAR FIRST YEAR POSTGRADUATE DEPARTMENT OF MICROBIOLOGY THANJAVUR MEDICAL COLLEGE

2. WIDAL TEST AIM: This diagnostic test is employed for the serological diagnosis of enteric fever.

3. PRINCIPLE TUBE AGGLUTINATION TEST: Antibodies against Salmonella typhi , S. Paratyphi A and B infections are detected in patient serum. Since two types of agglutinins are generated in the serum which react with ‘O’ and ‘H’ antigenic components of the salmonellae, a total of four antigen suspension namely TO, TH, AH and BH are employed in the test.

4. PROCEDURE Arrange four rows each containing 7 clean and dry W idal tubes (1:30, 1:60, 1:120, 1:240, 1:480, 1:960, NC) in a W idal rack for each antigen. So totally 29 tubes (including Master dilution tube) Mix 0.1 ml of the patient serum with 1.4 ml of the NS to obtain a 1 in 15 dilution (MASTER DILUTION) Add 0.4 ml of NS from 2 nd to 7 th tube of each antigen rows(O, H, AH & BH).

5. PROCEDURE (CONT.) Add 0.4 ml of already prepared Master diluted serum into 1 st and 2 nd tube of each antigen rows. After mixing, transfer 0.4 ml from 2 nd tube to 6 th tube and from sixth tube discard 0.4 ml (For all antigen rows) Add 0.4 ml of respective antigen namely TO, TH, AH and BH in respective rows from 1 st to 7 th tube. Incubate the tubes at 37 degrees celsius in water bath for 4 hours and read after overnight refrigeration at 4 degrees celsius .

6. INTERPRETATION O AGGLUTININ MORE THAN 100 - SIGNIFICANT TITER (Granular chalky clumps) H AGGLUTININ MORE THAN 200 - SIGNIFICANT TITER (Large loose fluffy cotton woolly clumps) BUTTON FORMATION – Agglutination doesn’t occur

7. WEIL FELIX TEST AIM: This diagnostic test is employed for the serological diagnosis of rickettsial infec tions .

8. PRINCIPLE HETEROPHILE TUBE AGGLUTINATION TEST: This test is based upon the sharing of an alkali-stable carbohydrate antigen between some rickettsiae and certain non-motile strains of Proteus, P.vulgaris OX19 and OX2 and P.mirabilis OXK. The antibodies against the pathogen appear around 5 th day of the onset of the disease. These can be detected by slide or tube agglutination.

9. PROCEDURE Arrange three rows each containing 7 clean and dry test tubes ( 1:20 , 1:40 , 1:80 , 1:160 , 1:320 , 1:640 , NC) in a test tube rack for each antigen. So totally 22 tubes (including Master dilution tube) Mix 0.1 ml of the patient serum with 0.9 ml of the NS to obtain a 1 in 10 dilution (MASTER DILUTION) Add 0.4 ml of NS from 2 nd to 7 th tube of each antigen rows(O X19, OX2 & OXK ).

10. PROCEDURE (CONT.) Add 0.4 ml of already prepared Master diluted serum into 1 st and 2 nd tube of each antigen rows. After mixing, transfer 0.4 ml from 2 nd tube to 6 th tube and from sixth tube discard 0.4 ml (For all antigen rows) Add 0.4 ml of respective proteus antigen namely OX19, OX2 & OXK in respective rows from 1 st to 7 th tube. Incubate the tubes at 50 degrees celsius in incubator for 4 hours and read after overnight incubation at 37 degrees celsius .

11. INTERPRETATION SINGLE TITRE OF >/=160 – CLINICALLY SIGNIFICANT (GRANULAR CLUMPS)

12. THANK YOU