Urinary Tract Infection - Risk Factors

Risk Factors of Recurring Infection in Women

Most women who have had one UTI have occasional recurrences, with between 25% and half of women can expect another infection within a year of the previous one.

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Between 3% of 5% of women, however, have ongoing, recurrent urinary tract infections, which follow the resolution of a previous treated or untreated episode. The major groups of women who are at highest risk for recurrent infections are young highly sexually active women and postmenopausal women. It might be argued that nearly all women who have a urinary tract infection are at risk for another, particularly if they are not treated for the first one.

Lifestyle Factors Increasing the Risk for Recurrence. Why urinary tract infections become chronic and recurring in many women is not entirely clear, but researchers are identifying certain lifestyle factors that may increase the risk in specific women:

Engaging in sexual intercourse more than four times a month.
Recent changes in sexual partners.
Having a mother with a history of UTIs.
Having a first UTI before age 15.
Use of spermicides.
Smoking and taking tub baths have also been implicated in increasing the risk for recurrent urinary tract infections, but they are less significant than other risk factors.

Biologic and Physical Factors. Some women may also have certain biologic or anatomical factors that increase the risk for recurring UTIs:

Having a shorter than average distance between the urethra and the anus.
Certain women may carry a compound called sialosyl galactosyl globoside (SGG) on the surface of kidney cells, which is a highly powerful receptor for E. coli bacteria.
Certain women have a genetic susceptibility to becoming infected in the vaginal area with greater numbers of disease-causing organisms that adhere to the lining.
Certain women may be deficient in human beta-defensin-1 (HBD-1), believed to be a naturally occurring antibiotic.

Risk Factors for Recurrence in the Aging Woman. In addition to menopause, other very strong risk factors for recurrences in older women include urinary incontinence and previous operations on the genital or urinary tracts. Additional risk factors for UTIs in older women include diabetes, vaginal itching or dryness, having had children, and poor overall health.

Risk Factors in Children

About 2% of children develop urinary tract infections. Because males are more likely to be born with structural abnormalities of the urinary tract, UTIs during the first six months of life are more common in boys. The rates are about equal in toddlers. Afterward, however, UTIs are far more common in girls. By the age of five, UTIs are 50 times more common in girls than in boys. Within the first ten years, boys will have a 1% and girls a 3% chance for developing a UTI. Recurrence will occur in about 30% of boys and 40% of girls.