A number of studies have pointed out the blunted clinical responses to bacteremia in elderly patients. It is clear that elderly patients may be bacteremic and remain afebrile.119Also, a significant proportion of patients may not have neutrophilia.120 Weakness and altered mental status may be the presenting symptoms.
The main sources of community-acquired bacteremia in the elderly, in order of decreasing frequency, are the urinary tract, intra-abdominal sites, and lungs.121 In long-term care facilities, the urinary tract is the most frequent source, followed by the respiratory tract.122Organisms most commonly recovered from patients with bacteremia associated with skin sources are S. aureus, S. epidermidis, gram-negative enteric bacteria, and anaerobes.121Bacteria from the urinary tract are usually gram-negative enteric bacteria or enterococci; from the biliary tract, gram-negative enteric bacteria or anaerobes; and from the respiratory tract, H. influenzae, S. pneumoniae, group B streptococci, or gram-negative enteric bacteria. Group G streptococcal bacteremia (usually from a cutaneous source) is especially common in the aged. In one recent review, the median age of patients was 72 years.123
Because of their increased risk for complications and higher mortality, elderly patients should be treated as soon as a presumptive diagnosis of bacteremia is considered. Selection of a proper antibiotic regimen is guided by the same principles as for younger individuals. Multidrug-resistant gram-negative bacteria are a disproportionately common cause of bacteremia among elderly residents of nursing homes.124 It is important to remember that elderly patients eliminate most antibiotics more slowly than younger individuals; dosages should be adjusted accordingly. Aminoglycosides, because of the increasing potential for toxicity with age, are best used with caution.125