Urinary Tract Infection - Risk Factors

Vesicoureteral Reflux (VUR). Vesicoureteral reflux (VUR) is the source of urinary tract infections in 30% to 50% of childhood cases. This is a structural defect of the valve-like mechanism between the ureter and bladder that allows urine to flow backward, carrying infection from the bladder up into the kidneys. VUR also puts children at risk for recurrence; such recurrences nearly always occur within the first six months after the first UTI.

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Risk Factors in Men

Men become more susceptible to UTIs after 50 years of age, when they begin to develop prostate problems. From 5% to 15% of men over 65 will have asymptomatic bacteriuria. Benign prostatic hyperplasia can produce obstruction in the urinary tract and increase the risk for infection. In men, recurrent urinary tract infections are associated with prostatitis, an infection of the prostate gland that can also be caused by E. coli.

Institutionalization

Hospitalizations and Catheters. About 40% of all infections that develop in hospitalized patients are in the urinary tract. The organisms that cause infections in hospitals (called nosocomial infections) are usually different from those that commonly cause UTIs. They are also more likely to be resistant to standard antibiotics. Hospitalized patients at highest risk for such infections are those with indwelling urinary catheters, patients undergoing urinary procedures, long-stay elderly men, and patients with severe medical conditions.

About 80% of UTIs in the hospital are due to catheters. Nearly all patients who need urinary catheters develop high levels of bacteria in their urine, and the longer the catheter is in place, the higher the risk for infection. Catheterized patients who develop diarrhea are nine times more likely to develop UTIs than are patients without diarrhea. In most cases of catheter-induced UTIs, the infection produces no symptoms. Because of the risk for wider infection, however, anyone requiring a catheter should be screened for infection. Catheters should be used only when necessary and should be removed as soon as possible.

Nursing Homes. All older adults who are immobilized, catheterized, or dehydrated are at increased risk for UTIs. Nursing home residents, particularly those who are incontinent and demented, are at very high risk. Up to 40% of elderly patients who live in nursing homes will contract a urinary tract infection. In most cases, the infections do not produce symptoms and are no more harmful than similar infections in the general population. Nursing home patients, however, are at higher risk for developing symptoms.