Name the test where secretion is mixed with a drop of 10% potassium hydroxide on a slide, providing a characteristic state fishy odour:
A. Nontreponemal tests
B. Treponemal tests
C. Rapid plasma reagin
D. Whiff test
Correct Answer: D. Whiff test
Explanation
The test you are referring to is the Whiff Test (also called the Amine Test).
Explanation:
- Procedure:
- A sample of vaginal secretion is placed on a glass slide.
- A drop of 10% potassium hydroxide (KOH) is added to the secretion.
- The slide is gently mixed, and the odor is observed.
- Observation:
- A characteristic “fishy” odor is produced if the test is positive.
- Clinical Significance:
- The Whiff test is used to help diagnose bacterial vaginosis (BV).
- The fishy odor comes from the amines (volatile nitrogen compounds) released by the overgrowth of anaerobic bacteria such as Gardnerella vaginalis.
- Why KOH?
- KOH increases the pH and releases volatile amines from bacterial degradation of proteins, which produces the odor.
✅ Summary:
- Test Name: Whiff Test / Amine Test
- Positive Result: Fishy odor after adding KOH
- Indicative of: Bacterial vaginosis
Other Options Details
Here’s a clear explanation of all the options you listed:
A. Nontreponemal tests
- Purpose: Screening tests for syphilis.
- How it works: Detects antibodies (reagin) that are not specifically directed against Treponema pallidum, but produced in response to cellular damage caused by the infection.
- Examples: VDRL (Venereal Disease Research Laboratory), RPR (Rapid Plasma Reagin).
- Use: Good for initial screening and monitoring treatment effectiveness, but can give false positives in other conditions (like autoimmune diseases, pregnancy, infections).
B. Treponemal tests
- Purpose: Confirmatory tests for syphilis.
- How it works: Detect antibodies specifically against Treponema pallidum.
- Examples: FTA-ABS (Fluorescent Treponemal Antibody Absorption), TP-PA (T. pallidum Particle Agglutination), EIA (Enzyme Immunoassay).
- Use: Confirms infection after a positive nontreponemal test. Usually remain positive for life, even after treatment.
C. Rapid plasma reagin (RPR)
- Type: Nontreponemal test.
- Purpose: Detects reagin antibodies in blood.
- How it works: Patient serum is mixed with an antigen; formation of clumps (flocculation) indicates a positive result.
- Use: Screening for syphilis and monitoring response to treatment (titers decrease after effective therapy).
- Note: Fast and inexpensive, but can give false positives.
D. Whiff test
- Purpose: Diagnostic test for bacterial vaginosis.
- How it works: Vaginal discharge is mixed with 10% potassium hydroxide (KOH) on a slide.
- Positive result: Characteristic “fishy odor” due to volatile amines released by anaerobic bacteria.
- Use: Simple bedside test to help diagnose bacterial vaginosis; not related to syphilis.
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Writer: Vandita Singh, Lucknow (GS India Nursing Group