The ASLO test, also called ASO, AEO or anti-streptolysin O, aims to identify the presence of a toxin released by the bacterium Streptococcus pyogenes , streptolysin O. If infection with this bacterium is not identified and treated with antibiotics, the person may develop some complications, such as glomerulonephritis and rheumatic fever, for example.
The main sign of infection with this bacterium is the sore throat that occurs more than 3 times a year and that takes time to resolve. In addition, if there are other symptoms such as shortness of breath, chest pain or joint pain and swelling, it is important to seek medical attention, as it may be rheumatic fever. Know what is rheumatism in the blood.
The test should be done on an empty stomach for 4 to 8 hours, depending on the recommendation of the doctor or laboratory, and the result is usually released after 24 hours.
What is it for
The doctor usually orders the ASLO exam when the person has frequent episodes of sore throat in addition to symptoms that may indicate rheumatic fever, such as:
- Fever; Cough; Shortness of breath; Pain and swelling of the joints; Presence of nodules under the skin; Presence of red spots on the skin; Chest pain.
Thus, based on the analysis of symptoms and the result of the exam, the doctor will be able to confirm the diagnosis of rheumatic fever, for example, which is characterized by a high concentration of anti-streptolysin O in the blood. Understand how to identify and treat rheumatic fever.
Streptolysin O is a toxin produced by a streptococcus-type bacterium, Streptococcus pyogenes , which, if not identified or treated with antibiotics, can cause rheumatic fever, glomerulonephritis, scarlet fever and tonsillitis, for example. Thus, the main means of diagnosing infection with this bacterium is through the identification of this toxin through the detection of antibodies produced by the organism against the bacterium, which is anti-streptolysin O.
Although positive results are characteristic of infection by Streptococcus pyogenes , not all people develop symptoms of rheumatic fever, glomerulonephritis or tonsillitis, for example, however they must be monitored by the doctor, performing periodic blood tests and cardiac check-up. See which tests are requested to assess the heart.
How is done
The ASLO test should be done on an empty stomach for 4 to 8 hours, according to the medical or laboratory recommendation and is done by collecting a blood sample that is sent to the laboratory for analysis. In the laboratory, the test is performed to detect the presence of anti-streptolysin O in the blood, which is done by adding 20µL of reagent, called Latex ASO, to 20µL of the patient's sample on a dark background plate. Then, homogenization is performed for 2 minutes and the particles are checked for agglutination in the plate.
The result is said to be negative if the concentration of anti-streptolysin O is equal to or less than 200 IU / mL, but this result may vary according to the laboratory where the test was performed and the person's age. If agglutination is found, the result is said to be positive, and successive dilutions are necessary to check the concentration of anti-streptolysin O in the blood. In this case, the doctor may request a new test after 10 to 15 days to check whether the concentration of anti-streptolysin decreases in the blood, is constant or increases and, thus, to check whether the infection is active or not.
In addition to the ASLO exam, the doctor may request a microbiological culture of material from the throat, as it is the location where the bacteria is normally present, to directly detect the presence of the bacterium Streptococcus pyogenes .
