What is an ASO test and how is it used to detect a bacterial infection of the throat?
Antistreptolysin O (ASO) titre is a blood test used to help diagnose a current or past infection with Group A strep (Streptococcus pyogenes). It detects antibodies to streptolysin O, one of the many streptococcus antigens. This test is rarely used now compared to thirty years ago. For an acute throat infection, this test is not performed; the throat culture is used. However, if a doctor is trying to find out if someone had a recent infection that may not have been diagnosed, this test could be helpful. In addition, it may be used to help diagnose rheumatic fever, which occurs weeks after a bacterial throat infection when the throat culture would no longer be positive.
