Question

Glomerulonephritis following streptococcal infection is diagnosed by which of the following tests?

• A. Blood culture
• B. Throat culture
• C. ASO titre
• D. PCR

Hint:

The organism is cleared by the time disease appears, so use a serological antibody test.

Answer 1

The Correct Option is C

Step 1: Post-streptococcal glomerulonephritis is an immune-mediated sequela that appears weeks after a group A streptococcal infection. By the time it presents, the organism has usually been cleared, so culture is often negative.

Step 2: The diagnosis is therefore retrospective and serological. It relies on demonstrating high levels of antibodies to streptococcal products, most commonly by the antistreptolysin O (ASO) titre. A titre above 200 units is considered significant and indicates recent or recurrent streptococcal infection.

Step 3: This makes ASO titre the correct answer. Blood culture and throat culture are frequently negative at this late stage, and PCR is not the standard tool for diagnosing this post-infectious condition.