The Antistreptolysin O (ASO) titer is a blood test that checks for a strep infection. A strep infection is an infection caused by the streptococcus group of bacteria. There are many different types of streptococci bacteria and these infections vary in severity from a mild throat infection to life threatening infections of blood or organs if neglected. The ASO titer test measures antibodies produced by your body in response to a toxin known as streptolysin O. your body makes the Antistreptolysin O antibodies when you have a strep infection caused by GAS bacteria.
