UTI prophylaxis

Recurrent urinary tract infections (UTI), defined as 2 or more infections in six months, or over three in a years period, is a frustrating disease for patients and physicians. This disease is common, where 20% of women presenting with a UTI will experience a recurrent episode at sometime. For the most part, these are new infections as opposed to persistence of the previous infection. When encountered, it raises the question as to whether patients should be treated with antibiotics on a more frequent basis in a prophylactic manner. Many women experience symptoms in relation to sexual activity, though in post-menopausal women, recurrent UTIs may have a different mechanism. Ageing results in changes in bladder function and anatomy, with increasing risk of prolapse. This can lead to urinary stasis and predisposition to recurrent UTIs. There are in general three approaches to this topic:


1. Continuous antibiotic prophylaxis
2. Post-coital prophylaxis
3. Intermittent therapy (not really preventative)

Choice of prophylactic strategy should be tailored to the individual patient. Cultures should be taken from the urine to confirm the presence of recurrent infection. Antibiotic choice should be based on culture and sensitivity results.

For women with recurrent UTI's, not in relation to coitus, continuous prophylaxis can be prescribed to patient as daily or three times weekly regiments. Usual antibiotics include: septra, nitrofurantoin, cephalexin, ciprofloxacin. Several studies have shown decreased rates of infection with this approach, and in 2004 a Cochrane review was published finding similar results. The number needed to treat in this review was 1.8 for one years therapy (which was the duration in the majority of studies). There was however increased side-effects in the therapy groups compared to placebo, where GI upset, rash and vaginal irritation was most common. In this study, there was no supreme antibiotics that performed better compared to others.
Following discontinuation of antibiotic therapy, women will tend to revert back to having recurrent UTI's. A reasonable approach is to trial antibiotics for 6 months, and after stopping see if the patient improves. Some individuals will have clusters of infection, which will be best treated with a period of drug followed by a holiday period. Longer prophylactic periods, upwards of two years, have also been advocated by some in the literature.

For females that develop infections in relation to sexual activity a post coital strategy can be taken, and has been found to have similar rates of success to continuous prophylaxis.  One study randomized 135 women to daily prophylaxis with 125mg of cipro versus a post coital strategy. They found similar results between groups and a third of the amount of antibiotic used. A study published in JAMA 1990, comparing placebo to septra using a post-coital strategy showed a significant reduction in UTI's. Where 81% in the placebo group developed a recurrent UTI compared to 12.5% in the therapy arm.

Intermittent therapy that is self administered is a useful approach for patients who are compliant and motivated. This strategy results in a higher number of infections, given it is not a truly preventative approach, but symptomatic duration and total antibiotic dosing is minimized. One study testing this approach found that symptomatic episodes had a culture negative rate of 14%, suggesting that women were able to accurate identify the presence of a UTI based on symptoms in over 85% of cases.

With the ever-growing use of antibiotics, resistance to these medications is a concern, and should be considered in patients receiving chronic therapy. There have been studies of patients taking chronic antimicrobial therapy for UTI prophylaxis identifying breakthrough infections with bugs that were resistant to the antibiotic prescribed. Separate studies using septra and cipro found breakthrough infection rates with resistant organisms at a rate of 44% and 3% respectively. This high rate of septra resistant organisms in this group is concerning, and provides some evidence that its use as prophylaxis results in significant alterations in microbe susceptibility patterns. See this NEJM review from 1993.

Urinary tract infections NEJM