Bacteremic superinfections of patients with bacteremia: occurrence, bacteriology, mortality, and duration of hospitalization at Boston City Hospital during 12 selected years between 1935 and 1972.

During the course of hospitalization of 6,414 patients with bacteremic infections identified at Boston City Hospital (Boston, Massachusetts) during 12 selected years between 1935 and 1972, 6.0% developed verified bacteremic superinfections with organisms not isolated or identified in the primary bacteremic infection. Analysis of these cases reemphasizes the increasing occurrence of serious hospital-acquired infections despite the successive introduction and intensive use of a large number of effective antibacterial agents. The bacteremic superinfections, like the primary hospital-acquired bacteremias, increased in incidence over the years, particularly since 1961; they were more frequent and were associated with a higher mortality rate and longer duration of hospital stay in the primary hospital-acquired cases than in the patients in whom bacteremia was considered to be community-acquired. The organisms in superinfections were similar to those in primary hospital-acquired bacteremias. Superinfection was more frequent among the patients who died than among the survivors.