Why aging leads to increased susceptibility to infection.

The elderly are predisposed to various infections through a multitude of factors. Although intrinsic, unalterable defects occur in the aging immune system and nonspecific host defenses, there are factors that physician and patient can concentrate on to reduce the risk of infection. For example, meticulous attention to skin care can reduce the risk of soft tissue infection. Improvement in oral hygiene and relief of xerostomia might promote recolonization with normal oral flora. Correction of urinary tract obstruction where possible, relying on the use of indwelling urinary catheters only when necessary, can significantly reduce the risk of UTIs. Medications that impair cognitive function should be prescribed judiciously, since they can promote aspiration with subsequent pneumonia, xerostomia, and urinary retention. Correction of protein malnutrition may improve cell-mediated immunity and skin integrity, thereby reducing the risk of infection. The signs and symptoms of infection in the aged may be subtle. Therefore, the primary care physician should approach this susceptible population with a heightened clinical suspicion, thus expediting possibly life-saving early diagnosis and treatment.