General principles in the laboratory detection of bacteremia and fungemia.

Various factors are important in the laboratory detection of bacteremia and fungemia. These include clinical factors, the type of blood culture system, and laboratory processing of blood culture bottles. Most commercial blood culture products have been designed to take these factors into account and, thus, are relatively similar. There are differences, however, and it should not be assumed that these products have identical performance characteristics. To optimize microbial recovery, clinicians should order and collect the proper number of blood cultures at the earliest possible time and before the administration of antimicrobial agents. Clinical microbiologists should select a blood culture system that optimizes the recovery of common microbial pathogens and should use blood culture systems according to the manufacturers' recommendations.