Blood culture test
A blood culture is a test to determine if micro-organisms (usually bacteria) are present in a person’s blood and what kind they are, so that they can be treated with an appropriate antibiotic. The test is done when doctors suspect that a patient has serious and widespread blood infections (such as bacteraemia or septicaemia), which may have spread from throat, skin, heart, and lung infections. Blood is drawn through a needle from a vein, usually on the inside of the elbow. The blood is sent to a laboratory for analysis, which can take several days.
What is it?
Blood culture is a blood test to determine if micro-organisms (usually bacteria) are present in a person’s blood.
Blood can be drawn in a doctor’s surgery, a clinic, or a hospital. The actual test is carried out in a laboratory.
Why is it done?
A blood culture is done when doctors suspect that a patient has bacteraemia or septicaemia (serious and widespread blood infections). These infections may have spread from other, primary, infections such as throat, skin, heart, and lung infections. Such patients are usually quite ill and are often hospitalised.
What happens?
Before – how to prepare
No special preparation is needed.
During – how the test is done
It is essential that the skin is sterile (free from all organisms) so that the blood specimen will not be contaminated. Your skin will be thoroughly cleaned to achieve this. A tourniquet or tight band is applied above the area in order to increase pressure and dilate the veins. A needle is then inserted, through the skin, into a vein (any vein can be used but those on the inside of the elbow are convenient), and some blood is withdrawn and placed in a special “culture bottle”. The needle may cause some pain but this is not usually severe.
The blood specimen is then sent to the laboratory where any organisms can be grown and identified. If an organism is isolated it can then be tested against antibiotics in order to determine which will be the most effective.
After the test
Any organisms need to be grown, which means that the results may take several days.
Risks and Compilations
Bruising at the site where the blood is drawn is the only real complication, although infection at this site is another possibility.
Special Issues
Blood culture results are not usually available for several days and so doctors will often need to give antibiotics without a clear diagnosis as to exactly which, if any, organisms, are involved.
It is common practice to perform repeated blood culture tests (often 3) so that any microorganisms are not missed.
Short Description
A blood culture is a test to determine if micro-organisms (usually bacteria) are present in a person’s blood and what kind they are, so that they can be treated with an appropriate antibiotic.
Keywords
blood culture, blood test, septicaemia, blood infection