Incidence and clinical significance of positive blood cultures in febrile episodes of patients with hematological malignancies.

The characteristics of 554 febrile episodes in 126 patients with a hematological malignancy over a 6-year period (1985-90) were reviewed in order to study the current incidence and clinical significance of blood culture positivity. An infection was documented microbiologically in 28% and clinically in 30% of the episodes. Blood cultures were positive in 19% of the febrile episodes. The rate of blood culture positivity was unrelated to the type of hematological malignancy, to neutropenia and to the presence of infection foci. 21% (26/126) of the patients died of sepsis-related causes. Sepsis-related death occurred in 23% of the blood culture positive febrile episodes, with a median survival time of 2 days. Infection prophylaxis did not reduce either the rate of blood culture positivity or the rate of sepsis-related deaths. Thus, the small proportion of febrile episodes whose fever etiology could be established by blood culture represented 'the tip of the iceberg', i.e. rapidly lethal septic infections with a high mortality rate. This fatality could neither be predicted by a search for infection foci nor prevented by infection prophylaxis.