The urinary tract makes and stores urine, which is produced in the kidneys and travels down the ureters to the bladder. The bladder stores urine until it is emptied by urinating through the urethra. Normal urine is sterile and contains no bacteria. Bacteria may get into the urine from the urethra, however, and this tends to increase with age. The September 2006 issue of "American Family Physician" featured an article on bacteruria which reports more than 20 percent of women who reach the age of 80 have bacteria in their urine, compared to 1 percent of girls under 14.
Estrogen Loss
Postmenopausal women have the highest risk for urinary tract infection or UTI, according to the University of Maryland Medical Center, or UMMC. Loss of the hormone estrogen has a thinning effect on the walls of the urinary tract, making these tissues more susceptible to infection. Without estrogen, vaginal cells lose resistance to E. coli bacteria, increasing pathogens that are in close proximity to the urethra. Soaps, lotions or excessive scrubbing may cause irritation and skin breakdown, increasing the likelihood of infection. The use of antibiotic medications can further increase growth of E. coli bacteria by killing off colonies of its natural enemy, the probiotic lactobacilli. Other medications, such as antihistamines in allergy or cough preparations, may cause increased tissue dryness and help trigger infection.
Urinary Retention and Incontinence
Age-related bladder prolapse, or cystocele, may interfere with complete emptying of the bladder. Nerve damage from a stroke may also cause urinary retention, which provides an opportunity for bacteria to proliferate. Urinary incontinence and leakage are also more common in elderly women; both contribute to the risk of urinary tract infection in this population. Severe retention or incontinence may necessitate placing a catheter in the bladder to collect the flow of urine; this is most often done in a hospital. According to UMMC, 80 percent of urinary tract infections that are acquired during hospitalization are a result of this procedure. The longer the catheter remains in place, the greater the risk of infection. Additionally, infection may be complicated because bacteria acquired in hospitals are more likely to be resistant to standard drug therapies. Women confined to long-term facilities are at increased risk of urinary tract infection due to immobilization, dehydration, incontinence and catheterization.
Diabetes
Elderly women with diabetes are at high risk of having bacteria in the urine that may cause no signs or symptoms. According to UMMC, this risk is correlated to the length of time a woman has had diabetes, regardless of how well her blood sugar has been controlled. Additionally, diabetes can cause nerve damage that leads to urinary retention. Renal impairment, kidney disease and fungal infections associated with diabetes may also increase the risk and severity of urinary tract infection.
