Widal Test
Sample collection and preparation:
1 This test can be used for serum, plasma, Heparin, sodium citrate, and EDTA can be used as the anticoagulant for plasma, whole blood, and fingertip blood. Samples should be free of hemolysis.
2. Suggest using the serum for better results.
3. If testing will be delayed, serum and plasma samples may be stored up to 7 days at 2-8'C or stored at -20 C for 6 months before testing (whole blood sample may be stored up to 3 days at 2 -8 C).
4. Refrigerated samples should reach room temperature and be homogeneous before testing. Avoid multiple freeze-thaw cycles.
5. Do not use heat-inactivated samples.
Typical salmonella components:
i. Somatic antigen ("O" antigen)
ii. Flagella antigen ("H" antigen)
iii. Surface antigen ("Vi" antigen)
Disease caused by Salmonella Typhi:
i. Typhoid fever
ii. Food poisoning
iii. Diarrhea
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| Typhoid Test Normal Range |
Slide method / Widal test:
Materials Required
Mention the materials needed for the test, including:
- Slide agglutination test kit
- Patient serum sample
- Reagent solutions (O antigen and H antigen, AH and BH)
- Sterile disposable pipettes
- Test tubes
- Mixing sticks
- Incubator
- Timer
Describe the widal test:
Widal test -it is the serological test for diagnosis of enteric fever The patient's serum is tested with O and H suspension of salmonella typhi, salmonella paratyphi-A, and salmonella paratyphi-B, widal test with commercially available stained as described-
In Rapid screening test :
Place two drops of undiluted serum and a drop of shaken Suspension. If agglutination is not visible within one minute, the test is negative. If agglutination is visible then the titration of serum is done on slide
Rapid slide titration Put up serum dilution of 1:20, 1:40, 1:80, 1: 160, and 1: 320 and one drop of suspension in each as per instruction in the leaflet. Find out the antibody titer
Tube agglutination test
# Make one row of serum dilutions for each suspension to be tested.
# Add antigen suspension
Result of widal test for typhoid fever-
Bacterial suspension Interpretation
TO Titre TH Titre
1:80 1:40 Normal
1 160 or more 1: 80 Typhoid fever
1: 160 or more 1: 160 or more Typhoid fever
1: 80 1: 160 or more Anamnestic reaction
Lab diagnosis of enteric fever / Typhoid fever :
i. Specimen collection:
· Blood for culture (1st & on the 2nd week)
· Serum for widal test(on the 2nd week)
· Stool for culture ( on the 3 weeks)
· Urine for culture (on the 4 weeks)
ii. Microscopic examination
It is not helpful
iii. Isolation and identification (Culture)
* Facultative anaerobic condition optimum temperature 37 overnight culture made on-
a. Blood culture: - Positive in 1s week of infection. Can be done in 3 processes.
# Traditional (Using liquid media on biphasic media)
# Lytic method (after processing in lytic solution in solid media)
# Automated (very raid within 6 hours)
b. Stool culture: - Positive from 2nd and 3rd week. It is done in-
· Mac-conkey's agar
· Deoxycholate citrate agar (DCA)
· Shigella salmonella agar media
c. Urine culture: - Positive show in 2nd and 3rd weeks. Culture in done in-
· Mac-conkey's agar
· Deoxycholate citrate agar (DCA)
iii.Serological test
· Widal test - Positive form 2nd week
Quality Control: Emphasize the importance of using positive and negative controls in each test to ensure accuracy.
Limitations: Explain how to report the results to the healthcare provider or patient.
Results: Mention the limitations of the Widal test, such as false positives or negatives.
Conclusion:
Summarize the key points of the Widal test procedure and its significance in diagnosing typhoid fever.
Note: In a presentation, you may want to include visual aids, diagrams, or actual images of the test procedure to enhance understanding. Additionally, ensure that your content is accurate and up-to-date based on the latest guidelines and protocols.
Precautions:
1. For the in vitro diagnostic use only
2. Do not use kit/devices/latex reagent beyond the expiration date
3. Do not use the test device/latex reagent if the foil pouch is damaged.
4. Do not open pouches until ready to perform the test
5. Do not reuse the device
6. Do not reuse the pipette
7. Handle all specimens as potentially infectious. proper handling and disposal methods should be followed in accordance with Reagent Company (WHO)regulations
8. Carefully visualize and follow the user manual to ensure proper test performance.
