Infectious Diseases in the Elderly

Document Type

Article

Publication Date

1-1-1983

Description

Several general statements about bacterial infection in elderly patients can be made. Some bacterial pathogens such as gram-negative bacilli and Listeria monocytogenes are more likely to occur in older patients than in younger adults, whereas other pathogens such as Type B Hemophilus influenzae are less likely to cause disease in the elderly. The diagnosis of bacterial infection in the elderly patient may be more difficult than in the younger adult. Elderly patients with pneumonia are less likely to complain of cough, and elderly patients with meningitis less likely to complain of stiff neck. In addition, some symptoms in elderly patients are more difficult to appreciate as clues to bacterial infection. In the elderly patient with meningitis, diagnosis may be delayed because a stiff neck was thought to represent cervical osteoarthritis. An elderly patient with a heart murmur and hemiplegia may be thought to have arteriosclerotic heart disease and a cerebrovascular accident, whereas in a younger patient the diagnosis of bacterial endocarditis would be made. The incident and mortality rates from many bacterial infections are higher in the elderly. The explanation for a higher incidence of infection in elderly patients is usually twofold: immunologic senescence, and associated predisposing illness. The relative importance of the two factors is not known for most infections. For example, the higher incidence of bacterial pneumonia in the elderly may be explained by the increased likelihood of aspiration secondary to cerebrovascular disease, esophageal motility disorders, or enteral feeding. However, the effects of senescence on pulmonary host defenses may be an equally important consideration. Meningitis may be more common in the elderly because of a higher incidence of pneumonia, neurosurgery, and urinary tract infection. However, Listeria monocytogenes meningitis probably occurs in the nondebilitated elderly patient more often than in the younger adult. The underlying pathogenesis of a bacterial infection may differ in the elderly population compared with a younger group. Bacterial endocarditis is more likely to be associated with nonrheumatic underlying disease, and urinary tract infection is more likely to be associated with prostatitis. Osteomyelitis is more likely to result from a contiguous focus of infection, whereas it is usually due to hematogenous spread in young adults. The treatment of bacterial infection in the elderly must take into consideration: the particular toxicity of some antibiotics in this group, the fact that dosage based on creatinine clearance changes with age, the existence of a larger variety of potential bacterial pathogens for most diseases, making empirical therapy more difficult, the more fulminant course of many bacterial infections in the elderly patient. With these basic principles stated, the authors discuss the specific characteristics of pneumonia, meningitis, endocarditis, and urinary tract infection in the elderly patient.

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