Blood culture is performed to isolate and identify bacterial pathogens, to diagnose and determine appropriate treatment for fever of unknown etiology and to diagnose endocarditis.
Blood cultures are performed to detect germs in the blood. Bacteremia (the presence of bacteria in the blood) can be intermittent and transient, except in cases of endocarditis and purulent thrombophlebitis. An episode of bacteremia is usually accompanied by chills and fever and therefore, blood cultures should be performed when the patient manifests these symptoms in order to increase the chances of isolation of the bacteria in the cultures. It is also important to obtain at least two culture samples from two different uptake sites. If one culture shows bacteria and the other does not, we can safely assume that the bacteria in the first culture may be a contamination rather than the actual infectious agent. When both cultures display the infectious agent, there is bacteremia and is caused by the organism developed in the cultures.
If the patient receives antibiotics during the culture, then a special resin is added to the culture medium to reverse the antibiotic activity in inhibiting the growth of the bacteria sought in the culture. Also, the blood sample should be taken shortly before the next dose of the antibiotic is administered. All cultures should be performed prior to initiating any antibiotic therapy.
Most organisms need about 24 hours to grow. Often, of course, it can take 48 to 72 or more hours for the organism to grow and identify. Anaerobic microorganisms and fungi may take longer to grow.
Possible Interpretations of Pathological Values
Laboratory test results are the most important parameter for the diagnosis and monitoring of all pathological conditions. 70%-80% of diagnostic decisions are based on laboratory tests. Correct interpretation of laboratory results allows a doctor to distinguish "healthy" from "diseased".
Laboratory test results should not be interpreted from the numerical result of a single analysis. Test results should be interpreted in relation to each individual case and family history, clinical findings and the results of other laboratory tests and information. Your personal physician should explain the importance of your test results.
At Diagnostiki Athinon we answer any questions you may have about the test you perform in our laboratory and we contact your doctor to get the best possible medical care.