Multiple-organism bacteremia in the surgical intensive care unit: a sign of intraperitoneal sepsis.

Multiple-organism bacteremia (MOB), as defined by the growth of two or more organisms in the same blood culture, was studied in the surgical intensive care unit at the Royal Victoria Hospital. Over the 2 years encompassing 1977 and 1978, there were 125 bacteremic episodes in 83 patients; of this total, 32 episodes of MOB were present in 27 patients. The mortality rate associated with MOB was 48% compared to 25% in those patients with a single organism in their blood (P less than 0.025). Three patients had two episodes of MOB, and one had three episodes; all died. The etiology in two patients was, surprisingly, intravascular devices. Two patients with four episodes of MOB had severe burns, whereas aspiration pneumonia and an infected amputation stump accounted for two more episodes. In the remaining 21 patients (78%) with 24 episodes of MOB (75%), all had intraperitoneal pathologic findings. Of these cases, 19 (59%) episodes were clearly related to intraperitoneal sepsis. The remaining five appeared related to intraperitoneal causes but were without confirmation. There was no difference in the incidence of Bacteroides and Staphylococcus epidermidis. The incidences of enterococci and Escherichia coli were significantly higher (P less than 0.005 for both) and dominant in multiple- versus single-organism bacteremia. Multiple-organism bacteremia is associated with an increased mortality rate, with origins characteristic of polymicrobial infections. The most important source is intraperitoneal and the occurrence of MOB should alert the surgeon to the likelihood of intraperitoneal sepsis.