Guideline for the Optimal Use of Blood Cultures (Guideline) (Report‪)‬

Detection of bacteraemia or fungaemia by blood culture is critical in managing patients with infection, and directs the appropriate selection of antimicrobials. Blood culture is a common laboratory investigation where blood is inoculated into culture medium and incubated. Media used in blood culture bottles support the growth of most medically important bacteria and fungi, including anaerobes, which grow adequately in the aerobic blood culture bottle, hence separate anaerobic bottles are infrequently used. (1,2) The goal of culturing blood is to determine whether a pathogenic microorganism(s) is responsible for the patient's clinical presentation. 'False positive' results occur when a skin commensal(s) rather than a true pathogenic organism is grown. Proper cleaning of the skin is a vital component of venesection to reduce the false-positive rate, yet poor technique is common when collecting blood for culture. This lapse results in inappropriate use of antibiotics, increased antibiotic resistance and prolonged hospital stay. A further barrier to correct laboratory interpretation of blood culture results is inadequate relevant clinical details on the accompanying request form. These guidelines contextualise the place of blood cultures in the management of sepsis and detail the appropriate method for acquiring blood for culture, to reduce the false-positive rate. Methods