Pemeriksaan Test Widal

Summary

This video provides an educational overview of the Widal test, a diagnostic procedure used to detect infections caused by Salmonella bacteria. The test involves analyzing the presence of agglutination in patient serum samples when exposed to specific Salmonella antigens. The procedure includes preparation of the serum and antigen, proper handling of reagents, and the use of a rotator to mix samples. Results are observed under a bright light, with agglutination at specific dilutions indicating the presence of the infection. The practical session concludes with a detailed explanation of the test's results, including positive reactions for O and H antigens at a dilution of 1/320.

Takeaways

• 😀 The Widal test is performed to identify serological reactions and diagnose infections caused by Salmonella spp.
• 😀 The Widal test helps detect agglutination in the blood serum when reacting with antigens.
• 😀 The Widal test can diagnose infections from Salmonella typhi and para-typhi (A, B, and C).
• 😀 Essential tools for the test include a slide with a white circle, mixing rods, micro pipettes, and a rotator.
• 😀 Antigens used in the Widal test include Salmonella typhi O, H antigens, and Salmonella para-typhi O, A, B, and C.
• 😀 The test involves adding serum samples at varying dilutions (1/20, 1/40, 1/80, 1/160, and 1/320) to test for agglutination.
• 😀 Antigen O and H are mixed with the serum in a systematic order for testing.
• 😀 The Widal test requires homogenization and careful mixing using separate mixing rods for each antigen.
• 😀 After mixing, the serum-antigen mixture is rotated for 1 minute to ensure proper reaction.
• 😀 The results are observed in a well-lit area to identify agglutination, which indicates the presence of infection, with the highest titer showing the strongest reaction.

Q & A

What is the main objective of the Widal test?

The main objective of the Widal test is to detect agglutination reactions in the serum, which helps diagnose infections caused by Salmonella, particularly Salmonella typhi and Salmonella paratyphi.

What are the primary materials needed for the Widal test?

The primary materials for the Widal test include a SL (slide), stirring rod, micro-pipettes, pipette tips, rotator, waste disposal container, serum, and various Salmonella antigens (O and H for typhi, and A, B, C for paratyphi).

How do you prepare the serum for the Widal test?

The serum is prepared by creating various dilutions. First, 80 µL of serum is pipetted at a 1/20 dilution. Then, 40 µL at 1/40, 20 µL at 1/80, 10 µL at 1/160, and finally 5 µL at 1/320.

How are the antigens added during the Widal test?

After preparing the serum dilutions, one drop of antigen O and one drop of antigen H are added to each dilution. The mixture is then homogenized using a clean stirring rod.

What is the purpose of using a rotator in the Widal test?

The rotator is used to mix the serum and antigen thoroughly for one minute. This ensures a uniform reaction and helps in the detection of agglutination.

How is the result of the Widal test observed?

After rotating the mixture, the results are observed under bright light for signs of agglutination. Agglutination indicates a positive reaction, which suggests the presence of Salmonella infection.

What does agglutination in the Widal test indicate?

Agglutination in the Widal test indicates a positive reaction, meaning the serum contains antibodies against Salmonella antigens, suggesting an infection.

What does a high dilution titer of 1/320 signify in the Widal test?

A high dilution titer of 1/320 signifies a strong positive result, indicating that the patient has a significant level of antibodies against the Salmonella antigens tested.

What is the significance of observing agglutination at different dilutions?

Agglutination at various dilutions helps determine the titer, or concentration, of antibodies in the serum. The highest dilution at which agglutination still occurs is the titer value, which indicates the strength of the immune response.

Why is it important to change the stirring rod when mixing the serum and antigen?

It is important to change the stirring rod each time to avoid cross-contamination between the different samples, ensuring accurate and reliable results.