patients with possible sepsis / septicaemia or infective endocarditis (including SBE) generally should have at least 2 sets of blood cultures taken (3 sets for suspected endocarditis), and preferably before commencing iv antibiotics
blood cultures can be taken from newly placed iv cannulae in the ED as long as the usual sterile technique is used 1)
in an ED setting, some 10% are likely to be true positives, whilst false positive contamination rates are usually around 3-4%