Recurrent Urinary Tract Infections in Women
By Abner Korn, MD, Professor of Clinical Obstetrics, Gynecology and Reproductive Sciences
University of California, San Francisco
Dr. Korn has disclosed that he has no financial interests related to this topic.
Urinary tract infections (UTI) are extremely common. There are more than 4 million office visits per year in the United States. More than half of all women will have a UTI during their life. Of these, one quarter will have at least one more infection in their lifetime. When more than two episodes of UTI occur in a year, the condition is called recurrent UTI.
Urinary tract infection occurs when the bacteria that cause it (such as E. coli, the most common cause of UTI) originate in the intestine, colonize in the vagina, and ascend into the urethra or bladder, often during sexual intercourse. Normally, vaginal lactobacilli (“good bacteria”) prevent growth of intestinal bacteria in the vagina. The hormone estrogen supports lactobacilli. After menopause, estrogen levels drop and so can lactobacilli numbers. This can make postmenopausal women especially susceptible to urinary tract infection. There are other normal defenses against UTI, such as the immune system. This can help block bacterial attachment to the cells lining the bladder and urethra and reduce the risk of UTI. Unfortunately, some women may inherit a weakness in the ability of their immune system to prevent bacterial adherence.
In pregnant women, treatment of asymptomatic bacteruria reduces their risk of getting a bacterial infection of the kidney (pyelonephritis). Asymptomatic bacteruria means that bacteria can be found in a urine test but the patient has no symptoms of UTI (burning with urination, frequency, urgency). This condition does not warrant treatment in postmenopausal women.
Sexual intercourse, use of contraceptive spermicide, low estrogen, catheterization, diabetes, pregnancy, and immune suppression increase susceptibility to UTI. The following methods can be used to help prevent UTI.
Use of cranberry products: cranberry seems to decrease the abilit of bacteria to adhere to the lining of the urethra and bladder. Studies show about 35 percent reduction in recurrence of UTI when the equivalent of eight ounces of cranberry juice is drunk daily. The high amount of sugar in cranberry juice may be of concern, especially for diabetics. An alternative is to use one of the preparations of cranberry extract sold in capsule forms.
Neither increasing fluid intake nor wiping from front to back after urination has been shown to reduce UTI. Contraceptive spermicide use doubles the risk of UTI. In postmenopausal women, the risk of UTI is tripled in the two days following intercourse compared to women who are not sexually active.
Vaginal (but not oral) estrogen use reduces recurrent UTI by 36 to 75 percent. Forms of vaginal estrogen are available that have minimal systemic absorption.
Probiotics (such as supplementation of vaginal lactobacilli) have not been shown to reduce UTI.
Antibiotic use reduces the risk of recurrent UTI by about 85 percent. In women who have sexually associated UTI, antibiotic use only after sexual activity is effective.
Immunotherapy: Uro-Vaxom is a product that is derived from the E. coli bacteria. When taken once daily the risk of recurrent UTI appears to decrease by nearly 50 percent. This product is available in Europe, but not in the U.S.
There are several treatments at hand that can help women prevent recurrence of UTI. This is important because UTI can lead to more serious infection and also because UTI has a negative impact on quality of life.
About the Author:
Dr. Abner Korn is the director of the Women’s Gynecologic-Urology Clinic. His special interests include female urology, incontinence, vaginal surgery, and gynecologic infections.