The changing epidemiology of bacteremia in neutropenic children with cancer.

Gram-positive bacteria have been the predominant organisms causing bacteremia in febrile neutropenic cancer patients during the past decade. Recently we have noted an increase in Gram-negative bacteremia in children and adolescents with cancer. Therefore we retrospectively reviewed 153 episodes of bacteremia during a 6-year period to investigate changes in the etiology of bacteremia in pediatric oncology patients. In the early 3-year period (January, 1988, to December, 1990) Gram-positive organisms comprised 73 (74%) of the 99 isolates, and Staphylococcus epidermidis was the most common isolate. In the later 3-year period (January, 1991, to December, 1993) Gram-negative organisms were seen with greater frequency and represented 50% of isolates (P = 0.004). Pseudomonas aeruginosa was the most commonly isolated organism during this period (22% of all isolates). We speculate that the recent utilization of more intensive chemotherapy regimens has caused an alteration in the epidemiology of bacteremia in children and adolescents with cancer which could influence the initial empiric antibiotic regimens and the outcome of such infections.