Bacteriuria and urinary infections in the elderly.

Aging is associated with a decreased physiological functioning, reflecting the body's progressive inability to maintain homeostasis as age increases. The physiologic dysfunctions experienced in response to the aging process increase the individual's susceptibility to infection. Many elderly subjects are hospitalized for the care and treatment of functional disabilities; thus, an increased exposure to possible uropathogens (many with antimicrobial resistance) often results in infection. Additionally, indwelling catheters and other attending procedures may provide a microenvironment conducive to infection. In catheterized patients, the drainage bag often is infected with polymicrobes, which enhances the transference of antimicrobial genetic information. Postmenopause reflects a decrease in circulating estrogen, and a relational decrease in lactobacilli colonization with a lower vaginal pH. Consequently, vaginal colonization with possible uropathogenic and gastrointestinal bacteria increases, which partially may account for the generally higher incidence of bacteriuria in elderly women as opposed to elderly men. Urinary infections in the elderly more commonly are asymptomatic. Treatment for asymptomatic bacteriuria is not justified and will often present opportunities for the infecting organism to acquire antimicrobial resistance. Only symptomatic bacteriuria presenting adverse conditions in the host should be treated. Antimicrobial selection for the treatment of complicating symptomatic urinary infections in elderly subjects is complicated by the many physiological and environmental conditions associated with older age patients. Unfortunately, data confirming the efficacy and safety of antimicrobial agents for the treatment of symptomatic infections in the elderly presently are insufficient.