Which antibody's titer indicates a recent infection with group A β-hemolytic streptococci?

Which antibody's titer indicates a recent infection with group A β-hemolytic streptococci?

• A. Anti-streptolysin S
• B. Anti-A
• C. Anti-streptolysin O
• D. Anti-B

Answer: (C)

The titer of anti-streptolysin O (ASO) antibodies is specifically linked to recent infections with group A β-hemolytic streptococci, commonly known for causing conditions like streptococcal pharyngitis and rheumatic fever. During an acute infection, the body produces antibodies against streptolysin O, a virulence factor secreted by these bacteria. A rise in ASO titers is typically observed within a few weeks following the infection and can remain elevated for some time, making it a reliable indicator of a recent streptococcal infection. Monitoring these titers can help clinicians confirm the diagnosis and assess the risk of complications associated with streptococcal infections. Other antibodies listed, such as anti-streptolysin S and anti-A and anti-B, do not specifically indicate infections with group A β-hemolytic streptococci. Anti-streptolysin S is not typically measured in clinical practice as ASO titers, and anti-A and anti-B relate to other conditions, primarily concerning blood types rather than infection status. Thus, assessing ASO titers remains the gold standard for identifying recent infections with the specific bacterial strain in question.

The titer of anti-streptolysin O (ASO) antibodies is specifically linked to recent infections with group A β-hemolytic streptococci, commonly known for causing conditions like streptococcal pharyngitis and rheumatic fever. During an acute infection, the body produces antibodies against streptolysin O, a virulence factor secreted by these bacteria.

A rise in ASO titers is typically observed within a few weeks following the infection and can remain elevated for some time, making it a reliable indicator of a recent streptococcal infection. Monitoring these titers can help clinicians confirm the diagnosis and assess the risk of complications associated with streptococcal infections.

Other antibodies listed, such as anti-streptolysin S and anti-A and anti-B, do not specifically indicate infections with group A β-hemolytic streptococci. Anti-streptolysin S is not typically measured in clinical practice as ASO titers, and anti-A and anti-B relate to other conditions, primarily concerning blood types rather than infection status. Thus, assessing ASO titers remains the gold standard for identifying recent infections with the specific bacterial strain in question.