Factors that may affect blood culture result

Blood culture test is done to determine infection presence in blood. No microorganisms are found in blood in normal conditions. Microorganism presence in blood is a life-threatening condition so it must be diagnosed and treated as soon as possible.  Blood culture determines bacteria or fungi presence in blood circulation. Sometimes blood culture test may not be valid, may be false or blood culture test can’t be done by some factors;

Recently antibiotic usage

blood-culture-analyzerAntibiotics prevents bacteria growth and so prevents blood culture test to result. You should not use antibiotics without asking your doctor. If you used antibiotics recently before blood culture test please inform your doctor about this. A certain time must be passed after antibiotic usage to have the blood culture test or other culture tests like urine culture, semen culture, ear drainage culture, etc.

Contamination during blood collection

Blood collection site must be cleaned very well before the process by an antiseptic. Also phlebotomist ( nurse,technician) should be careful about the laboratory equipment. False positive result may be found because of the bacteria or fungi that came from your skin, equipment or environment instead of your blood. Blood culture test result may be found positive but it will be hard to understand whether the positive bacteria are the cause of infection or not.

Blood collection time

Blood collection should be done when the germs are present in the blood circulation otherwise blood culture test result may not be proper. This is the reason of collecting blood in different times for blood culture test.

Laboratory conditions

Blood culture test bottles (liquid media) should be delivered to the laboratory as soon as possible. Laboratory process should be started in a short time. Blood culture bottles should be inoculated in proper conditions. Today automated blood culture analysers are used in hospitals that inoculates blood culture bottles in body temperature and provides information about bacterial growth.


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