Which serologic test is commonly positive after a streptococcal infection causing PSGN?

Which serologic test is commonly positive after a streptococcal infection causing PSGN?

• A. Anti-DNase B
• B. ANA
• C. ANCA
• D. anti-dsDNA

Answer: (D)

Post-streptococcal glomerulonephritis reflects a prior group A Streptococcus infection, and the body’s immune response produces antibodies against streptococcal enzymes. Anti-DNase B is such an antibody and is commonly elevated after a streptococcal infection, including skin infections, making it a reliable marker to document recent exposure in the PSGN setting. It tends to remain elevated longer than some other streptococcal antibodies, which is why it’s frequently used to confirm the connection between the infection and subsequent glomerulonephritis. By contrast, antibodies like ANA and anti-dsDNA are associated with autoimmune diseases such as lupus, and ANCA is linked to certain vasculitides; none of these specifically indicate a recent streptococcal infection, so they aren’t expected to be positive due to PSGN from GAS.

Post-streptococcal glomerulonephritis reflects a prior group A Streptococcus infection, and the body’s immune response produces antibodies against streptococcal enzymes. Anti-DNase B is such an antibody and is commonly elevated after a streptococcal infection, including skin infections, making it a reliable marker to document recent exposure in the PSGN setting. It tends to remain elevated longer than some other streptococcal antibodies, which is why it’s frequently used to confirm the connection between the infection and subsequent glomerulonephritis. By contrast, antibodies like ANA and anti-dsDNA are associated with autoimmune diseases such as lupus, and ANCA is linked to certain vasculitides; none of these specifically indicate a recent streptococcal infection, so they aren’t expected to be positive due to PSGN from GAS.