Understanding the blood culture report.

There are no hard-and-fast rules for judging whether an organism is a pathogen or contaminant. Experience is critical. In the end, the physician is responsible for determining whether an organism is a contaminant or a pathogen on the basis of laboratory and clinical data, which often include patient history, physical examination, body temperature, peripheral leukocyte count and differential, clinical course, and culture results. When blood culture results are given to a nurse, she or he should communicate this information to the attending physician as soon as possible, with greatest emphasis placed on positive cultures with probable pathogens. The assumption that a blood culture isolate is a pathogen, in the absence of other supporting facts, can lead to inappropriate therapy. On the other hand, assuming a pathogen to be a contaminant can ultimately lead to patient mortality if treatment is delayed. Questions as to how blood cultures are handled should be directed to microbiology personnel, whereas interpretation problems should be discussed with infectious disease specialists. Good communication among the nurses, laboratory personnel, and physicians involved with blood culture studies is invaluable to effective patient care.