Test Catageory
فئة التحليل
Immunology
Refrence Books
كتب مراجع
1. Basic Immunology: by Abul K. Abbas
2. Kuby Basic Immunology
Skills Required
المهارات المطلوبة
1. Good micropipetting technique
2. Ability to recognize agglutination reactions
3. Knowledge of QC and interpretation of results
Video Resources
مصادر فيديو
Principle
Anti-Salmonella O and H antibodies in patient serum samples form clumps when mixed with O and H antigen-coated latex beads, indicating a positive agglutination reaction.
Solutions & Equipments
1. Widal Salmonella Antigen suspension (TO, TH, AO, BH)
2. positive and negative control sera
.3. disposable 10, 20 or 50 μL micropipettes
4. timer
l5. Latex slide agglutination plate
Sample Type
Serum Samples are Best Choice for Widal Test
Procedure
1. Bring all reagents and samples to room temperature
2. Mix latex antigen suspension well before use
3. Add 40 μL serum to a circle on agglutination slide
4. Add 40 μL latex antigen suspension to the serum
5. Mix serum and antigen using a clean mixing stick for each sample
6. Rock slide gently by hand for 2 minutes
7. Read presence or absence of visible clumping immediately after 2 minutes
Results
The result is interpretated as Titer Based on the Agglutination
The titer is defined as the highest dilution of patient serum that produces a visible positive agglutination reaction with the antigen suspension.
To determine antibody titer by the slide method:
1. Prepare serial 2-fold dilutions of patient serum sample in 0.9% saline across 6 circles on the latex slide. Dilutions are 1:20, 1:40, 1:80, 1:160, etc.
2. Add an equal volume (40 μL) of the standardized latex antigen suspension to each serum dilution.
3. Mix with separate mixing sticks and rock gently for 2 minutes.
4. Read presence of agglutination in each serum dilution immediately after 2 minutes.
5. The titer is reported as the reciprocal of the highest dilution showing a positive 1+ or greater agglutination. For example, agglutination visible up to 1:160 serum dilution is reported as a titer of 160.
6. Titers ≥ 1:80 for TO and TH antigens are highly suggestive of recent enteric fever infection with Salmonella Typhi.
7. Titer results should be considered along with clinical findings for diagnosis of enteric fever. Paired acute and convalescent samples may show rising antibody titers.
Notes:
Check positive and negative control reactions prior to interpretation of sample results. Report semi-quantitative titer based on agglutination reaction strength.
M. Sulieman
mohammad@mlsgaate.com
Check positive and negative control reactions prior to interpretation of sample results. Report semi-quantitative titer based on agglutination reaction strength.
