Antistreptolysin 0 (ASO)

 

Indications:

Streptococcal infection is detected by the presence of ASO (antistreptolysin O), group A, C or G Lancefield.

On the research in the following diseases: rheumatic fever, scarlet fever, glomerulonephritis or endocarditis.

Faced with persistent or recurrent angina, consideration is large diagnostic and preventive interest.

Principle:

Streptococcal of Beta-hemolytic group A produce two hemolysis, responsible for erythrocyte hemolysis accompanying infection, this being due to its affinity for oxygen; one of them is streptolysin O, easily detected by the antibodies it causes. His presence sign a streptococcal infection.

Antistreptolysin 0 (ASO)Technique:

Sampling 10 mL of blood on dry tubes, avoiding hemolysis serum by stirring the tube. An icteric serum or hyperlipemia does not correctly determine the amount of ASO.

The assay is to measure the neutralizing capacity of the patient serum by a calibrated metering streptolysin O. reference

Results:

The rate is rarely zero because of the frequency of streptococcal infections in infancy. And a lower rate to 200 IU / mL is it regarded as not reflecting recent infection.

Above 300 IU / mL, the rate is indicative of a streptococcal infection.

However, a better result obtained from the comparison made between two levels at 15 day intervals.

This remark limit the interest in this case the dosage, healing may precede obtaining laboratory results, all the more so that early antibiotic therapy rapidly reduces the rate or prevents the rise.

So many limits on medical use.

Cost:

B30.

Practical advice:

The rise of ASO is significant at day 10 of infection and decreases the 30th. However, 20% of A streptococcal infections do not have elevated ASO.

A rapid test for strep in the medical practice for deciding the need for antibiotics before angina.

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