Gram-negative Bacillary Bacteremia in the Elderly: Incidence, Ecology, Etiology, and Mortality

The incidence, ecology, and mortality of gram-negative bacillary bacteremia in elderly patients were studied in an analysis of 334 episodes over a four-year-period in a 489-bed North Carolina community teaching hospital, 135 (40.4%) of which occurred in patients 70 years of age or older. The bacteremia rate per 1000 hospital admissions increased sharply with increasing age. The ecology and in vitro antimicrobial susceptibilities of the bacterial isolates were strongly influenced by community v hospital acquisition, but not by age. Urosepsis was significantly more likely to be the underlying source of hospital-acquired bacteremia in patients 70 years or older (P less than 0.01). Total bacteremia-related mortality did not increase with increasing age; in the group of patients aged 70 years or older with nonfatal/ultimately fatal underlying diseases (NF/UFUD), however, mortality was 9.1% compared to 2.9% in the younger age group (P less than 0.001). Significantly increased bacteremia-related mortality was also noted in the older patients with NF/UFUD admitted from nursing homes (P less than 0.05) and those not treated with an appropriate antimicrobial agent within 24 hours (P less than 0.01). Overall, the older patients with hospital-acquired bacteremia, neutropenia-associated infection, those bacteremic from a nonurinary source of infection, and those treated with multiple-drug regimens had higher mortality (P less than 0.05). Gram-negative bacteremia is much more common in patients 70 years of age or older and compared with younger patients mortality appears to be significantly increased for the important subgroup of older patients with nonfatal or ultimately fatal underlying diseases.