Urinary tract pathogens in complicated infection and in elderly individuals.

Complicated urinary tract infection (UTI) occurs in patients7 with a genitourinary tract that does not function normally, usually due to structural or functional abnormalities. There are a wide variety of diseases and interventions responsible for complicated UTI, including obstructive lesions, metabolic diseases, instrumentation, foreign bodies, or dysfunctional voiding primarily due to neurologic illnesses (figure 1). The wide variation in abnormalities means there is substantial variation in the clinical characteristics of UTI in these different populations. For instance, in some patients with a nonfunctioning kidney, once infection is established, it usually cannot be eradicated, and relapsing infection with the same organism will persist. Another group of patients, those with neurogenic bladder and voiding managed by intermittent catheterization, have a high incidence of infection with new infecting organisms, which are constantly introduced into the urinary tract. In other instances, such as infection associated with obstruction when a stone is passed, correction of the abnormality (i.e., removal of the stone) will alleviate the complicating factor, and further infection is unlikely to occur. This great diversity in risk factors and natural history must be appreciated in any discussion of complicated UTI. UTI among elderly populations is very common and is conceptually considered within the context of complicated UTI [1]; that is, the genitourinary tract is not functioning normally. In ambulant elderly women, prior genitourinary surgery and abnormalities, such as cystoceles, are associated with infection, and in men, prostatic hypertrophy is an important association with infection. These are common abnormalities recognized to be associated with an increased frequency of UTI at any age. In the institutionalized elderly population, the major contributing factors to infection are chronic comorbid neurologic illnesses with an associated neurogenic bladder. Thus, UTI in the institutionalized population is generally an accompaniment of incontinence and dementia.