Asymptomatic bacteriuria in elderly patients: significance and implications for treatment.

Asymptomatic bacteriuria (ASB) is frequent in elderly patients and even more prevalent in residents of long-term care facilities. Furthermore, because more and more people are reaching advanced age and the need for care increases with age, ASB is becoming increasingly important. There are several definitions for ASB, all of which require positive urine cultures and place little or no importance on accompanying pyuria. Most ASB is associated with complicating factors, as might be found in complicated urinary tract infections (UTIs). Thus, the bacterial spectrum associated with ASB is comparable to that seen in complicated UTIs. A variety of complicating factors are more frequently found in elderly patients with ASB, such as hormonal factors (e.g. estrogen decrease), certain anatomical factors (e.g. prostate obstruction), metabolic factors (e.g. diabetes mellitus), functional alteration of the urinary bladder, immunological changes and a high rate of indwelling-catheter use. Screening for ASB in elderly people is limited to those undergoing invasive urological procedures and surgical procedures with implant material. In other situations, examination of the urine is not recommended if signs or symptoms in the urinary tract are absent. Treatment of ASB is recommended only before urological procedures. Pyuria accompanying ASB is not an indication for antimicrobial treatment. If antimicrobial treatment is considered, concomitant factors that occur frequently in elderly people, such as renal insufficiency, must be taken into account. Although ASB is apparently a benign condition, prevention in elderly people is important. The degree of pathogenicity of bacteria causing ASB has not yet been satisfactorily elucidated. Therefore, until the implications of the bacteria involved in ASB are fully understood, implementing the same hygienic precautions as are used in individuals with symptomatic UTIs should at least be undertaken.