Bloodstream infections in the elderly

Abstract 

purpose: Bacteremia in the elderly is associated with a different clinical course and a higher mortality rate when compared with that in younger age groups. In order to examine these issues in the aged, we reviewed the clinical course and factors involved in the outcome of 100 episodes of bloodstream infections in patients over 65 years of age.

patients and methods: The hospital records of all patients over 65 years of age at The Mount Sinai Hospital with a positive blood culture result during the period October 1984 to October 1986 were reviewed. Place of residence before hospital admission, site of acquisition of infection, source of bloodstream infection, and microorganism were analyzed. Antimicrobial therapy was defined as appropriate if initial therapy included one agent to which the isolate was sensitive, or inappropriate if the isolate was resistant. The following factors affecting survival were analyzed: age, sex, underlying diseases, clinical parameters on admission, white blood cell count, mental status, source of infection, microorganism isolated, antibiotic toxicity, and appropriate versus inappropriate antibiotic therapy.

results: Most patients were female (63 percent), were febrile (90 percent), had an altered mental status (52 percent), and had a neutrophilic response (61 percent). Eighty-three percent of patients were admitted from the community (home), 14 percent were from long-term-care facilities, and 3 percent were transferred from other hospitals. Fifty percent of infections were nosocomial, and 44 percent were community (home and nursing home)-acquired. Gram-negative organisms accounted for 60 percent of isolates, with Escherichia coli (22 percent) and Klebsiella species (11 percent) predominating; 30 percent were gram-positive organisms, with Staphylococcus aureus (13 percent) and Streptococcus faecalis (10 percent) the most common. The overall survival was 60 percent; the survival rate was 65.8 percent for community-acquired (home) bacteremia, 75 percent for nursing home-acquired bacteremia, and 52.8 percent for hospital-acquired bacteremia. Survival for gram-negative isolates was 65 percent, versus 51.7 percent for gram-positive isolates. Survival was greatest in patients whose source of bacteremia was either the genitourinary tract (70 percent) or an intravascular device (78 percent) and poorest in patients with lower respiratory tract source (42 percent); all three patients with endocarditis died. Increased survival was observed in patients treated with appropriate antimicrobial agents regardless of age, source of infection, or bloostream isolates. Inappropriate therapy, in conjunction with age greater than 85 years or with S. aureus infection, was associated with increased mortality. Toxicity was greatest with aminoglycosides (21 percent), followed by cephalosporins (19 percent), and was least with pencillins (12 percent); fewer cases of ototoxicity and nephrotoxicity were observed in aminoglycoside-treated patients older than 85 years compared with that in younger age groups.

conclusion: The data suggest that initial empiric antimicrobial therapy in the elderly be broad in scope and include coverage for S. aureas. Particular attention is necessary in selecting appropriate initial therapy in patients greater than 85 years of age.

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