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Am Fam Physician. 2005;71(7):1301-1302

Clinical Scenario

A 26-year-old woman visits your clinic with dysuria. She is diagnosed with her fourth urinary tract infection (UTI) of the year.

Clinical Question

Should we use prophylactic antibiotics in patients with recurrent UTIs? If so, which antibiotic and schedule are best?

Evidence-Based Answer

Prophylactic antibiotics can reduce the number of recurrent UTIs in nonpregnant women while they are taking the medication (relative risk [RR], 0.21; number needed to treat [NNT], 2). No antibiotic was significantly better than others at decreasing the number of UTIs, and all antibiotics caused side effects such as candidiasis, rash, and nausea in some patients. Postcoital prophylaxis was as effective as daily prophylaxis in young women. Limited evidence suggests that weekly prophylaxis is better than monthly prophylaxis, but the former has not been compared with daily or postcoital prophylaxis.

Cochrane Abstract

Background. UTI is a common health care problem. Recurrent UTI in healthy, nonpregnant women is defined as three or more episodes of UTI during a 12-month period. Long-term antibiotics have been proposed as a prevention strategy for recurrent UTI.

Objectives. To determine the efficacy (during and after) and safety of prophylactic antibiotics used to prevent uncomplicated recurrent UTI in nonpregnant women.

Search Strategy. The authors1 searched MEDLINE (1966 to April 2004), EMBASE (1980 to January 2003), Cochrane Register of Controlled Trials (in the Cochrane Library Issue 1, 2004), and reference lists of retrieved articles.

Selection Criteria. Published randomized controlled trials (RCTs) in which antibiotics were used as prophylactic therapy in patients with recurrent UTI were selected.

Data Collection and Analysis. Two reviewers independently assessed trial quality and extracted data. Statistical analyses were performed using the random-effects model, and the results were expressed as RR with a 95 percent confidence interval (CI).

Primary Results. Nineteen studies with a total of 1,120 women were eligible for inclusion. Of these, 10 trials with 430 women compared antibiotics with placebo. During active prophylaxis, the rate of microbiologic recurrence per patient-year was 0 to 0.9 in the antibiotic group compared with 0.8 to 3.6 in the placebo group. The RR of having one microbiologic recurrence was 0.21 (95 percent CI, 0.13 to 0.34), which favored antibiotic, and the NNT was 1.85. The RR for clinical recurrences was 0.15 (95 percent CI, 0.08 to 0.28), and the NNT was 1.85. The RR of having one microbiologic recurrence after prophylaxis was 0.82 (95 percent CI, 0.44 to 1.53). The RR for severe side effects was 1.58 (95 percent CI, 0.47 to 5.28); the RR for other side effects was 1.78 (95 percent CI, 1.06 to 3.00), which favored placebo. Side effects included vaginal and oral candidiasis and gastrointestinal symptoms. Eight trials with 513 women compared antibiotics; these trials were not pooled. Weekly prophylaxis with pefloxacin was more effective than monthly prophylaxis. [NOTE: pefloxacin is a fluoroquinolone that is not available in the United States.] The RR for microbiologic recurrence was 0.31 (95 percent CI, 0.19 to 0.52). There was no significant difference in rates of microbiologic recurrence with daily and postcoital ciprofloxacin.

Reviewers’ Conclusions. Compared with placebo, continuous antibiotic prophylaxis for six to 12 months reduced the rate of UTI during prophylaxis. After prophylaxis, two studies showed no difference between groups. The treated group had more adverse events. One RCT compared postcoital and continuous daily ciprofloxacin and found no significant difference in rates of UTI, suggesting that postcoital treatment could be offered to woman who have UTI associated with sexual intercourse.

These summaries have been derived from Cochrane reviews published in the Cochrane Database of SystematicReviews in the Cochrane Library. Their content has, as far as possible, been checked with the authors of the originalreviews, but the summaries should not be regarded as an official product of the Cochrane Collaboration; minorediting changes have been made to the text (

Practice Pointers

About 40 percent of all women will report having a UTI during their lives.2 Some studies estimate that 20 percent of young women with acute cystitis will develop recurrent episodes.1

Risk factors for developing UTI in women include sexual intercourse, spermicide and diaphragm use, and a history of recurrent UTI.3 Other risk factors include having a first UTI at age 15 or younger and a mother with a history of UTI.4 After menopause, risk factors include cystocele, incontinence, and postvoiding residual urine.5

There are many options for treating recurrent UTI. This review showed that prophylactic antibiotics are better than placebo in reducing the number of recurrences. The NNT to prevent one symptomatic recurrent UTI in one year was 2.2. However, after prophylactic therapy was stopped, rates of recurrence were equal to those in women who did not receive prophylactic therapy. The reviewed studies showed that side effects with the antibiotics were common and included nausea, rash, and oral and vaginal candidiasis. The number needed to harm for any side effect was 13.5.1 Thus, if 14 women are treated with antibiotic prophylaxis for one year, seven will have one fewer recurrent UTI, and one will experience a side effect.

Schedules for management of recurrent UTI include daily, weekly, or monthly prophylaxis, postcoital prophylaxis, and acute self-treatment.6 One study showed that sexually active young women who took postcoital ciprofloxacin had similar outcomes to women who took ciprofloxacin daily. Another study showed that weekly prophylaxis was better than monthly prophylaxis. No studies compared daily and weekly prophylaxis.1

There are various antibiotics to consider in treating recurrent UTI. Antibiotics included in the review were fluoroquinolones, first-generation cephalosporins, trimethoprim, sulfamethoxazole, and nitrofurantoin. The review found that no antibiotic was superior.

Family physicians must weigh the costs versus the benefits when deciding whether to use prophylactic antibiotic treatment in patients with recurrent UTI. The decision to start prophylaxis should be individualized and based on the patient’s preferences. Multiple factors must be considered, including the severity of UTI symptoms, cost, hassle, antibiotic resistance, and potential side effects. In patients who prefer not to use antibiotic prophylaxis, well-established protocols are available for empiric treatment by telephone.

These are summaries of reviews from the Cochrane Library.

This series is coordinated by Corey D. Fogleman, MD, assistant medical editor.

A collection of Cochrane for Clinicians published in AFP is available at

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