Information About ASOT (Antistreptolysin O Titer) Serum Test

Submitted on March 27, 2012

The Antistreptolysin- O titer test or the Antistreptolysin O titer serum test (ASOT serum test) is used to test for the presence of the Streptococcus pyogenes bacteria which cause many serious medical conditions. Streptococcus pyogenes bacteria have been associated with rheumatic fever and acute glomerulonephritis.

The bacteria belong to the family of A β-hemolytic streptococci, which produce dangerous toxic compounds in the body. These toxins, which act as antigens, can cause various diseases in the body. One of the toxins produced by these bacteria is known as streptolysin O.


A person who is infected with these bacteria and specifically with the exotoxin streptolysin O generates specific antibodies. The amount of antibodies produced is directly correlated with the degree of infection and the extent of its spread.

ASOT test method is based on a reaction between the streptococci exotoxins and the latex particles to which they are bound, with the antibodies of streptococci in the sample. This is an immunological reaction that usually occurs naturally in the body. When the level of antibodies increases, there is an agglutination which is quite visible.

This medical test is specifically ordered when rheumatic fever or an infection due to the streptococci infection is suspected. Fresh serum that is taken from a vein using a puncture by an injection is used as the specimen on which the test is performed. The sample should be centrifuged before storing so that the fibrin is eliminated.

If the sample has been hemolised or is lipemic, it is rejected and a new sample is drawn. When the sample is handled, it has to be ensured that clots are completely formed. The sample is once again centrifuged so that serum, which is free of both fibrin and red blood cells, can be obtained.

Procedure to Conduct The Test

The test procedure is quite complicated and the reagent and sample are both allowed to reach room temperature after being removed from the freezer. Once the temperature has been reached, on two separate slides, a drop of sample is placed. To one slide, positive control is added and to the other, negative control is added. Next, a drop of the latex reagent should be added to the sample that has to be tested. Stir the sample well with a stirrer and then rotate the slide with the help of a mechanical rotator. A positive sample will have ASOT concentration more than 200 IU/ml.

A glossy and hemolysed sample should never be used for this procedure. Doing so can affect the test results.

ASOT Serum Levels Test

Doctors recommend an ASOT serum levels test (also known as the Antistreptolysin O titer serum test) to check the blood serum for bacterial contaminants such as the streptococcus pyogenes. These bacteria can cause a number of serious medical problems. These bacteria may cause acute glomerulonephritis and rheumatic fever. The bacteria can produce several toxic products in the body, therefore causing several serious health problems. These toxins trigger the immune system and produce some specific antibodies that can be tested and found in the blood serum to indicate the presence of the bacteria.

One of the chief causes of testing for ASOT serum levels is bacteria related illnesses. If a person is infected with the streptococcus bacteria, a toxin known as streptolysin O is generated in the body. This toxin generates antibodies that can be analyzed to check the extent to which the infection has spread in the body. ASOT serum results can help the doctor determine the appropriate course of treatment. The severity of infection can be determined based on the level of antibodies produced due to the toxins. If the level of antibodies is very low, the infection is usually very mild. However, if the antibodies are present in large numbers, they can indicate a severe infection. The ASOT serum analysis can help the doctor find out the extent of the infection, and therefore, determine the course of treatment that could best address the infection.

ASOT Serum Screening Test & Analysis

ASOT serum screening test is based on the reaction that occurs between the toxins produced by streptococcus as well as the latex particles that are introduced into the serum to bind the toxins. The test also checks for antibodies in the blood serum. The doctor would prescribe this test if you are experiencing symptoms of rheumatic fever or a suspected infection with the streptococci bacteria. The ASOT serum levels analysis is performed through a simple blood test. Blood is extracted from the vein and the sample is centrifuged to prevent clotting. After the fibrin is removed, the sample is stored and tested for the antibodies.

The procedure is simple and there are minimal risks or side effects to the test. If the sample has clotted or has hemolised, you may have to give a fresh sample. If the ASOT concentrations in the blood serum levels are less than 200 IU/ml, it is considered to be normal or healthy. However, if the ASOT concentrations are higher, the test is considered positive and an antibacterial treatment course may be prescribed by the doctor.