Bacteria in blood smears: overwhelming sepsis or trivial contamination.

It is unusual to find microorganisms in peripheral blood smears, and their presence is frequently associated with overwhelming sepsis and consequently a poor prognosis. In this report, we demonstrate 4 cases with bacteria in blood smears. Two of them had a fatal outcome, but the other 2 were caused by a contamination either via the central venous catheter or in vitro, both without dramatic outcome. The finding of bacteria in blood smears has to be interpreted carefully, and thorough examination of peripheral blood smears may be of great importance in the early diagnosis of bacteremia; however, in vitro contamination must be excluded.