Can a Silent Kidney Infection or Genetic Predisposition Underlie Recurrent UTIs?

, University of Calgary and Alberta Children's Hospital


Medscape General Medicine. 1996;1(1) 

In This Article

Managing a Reinfection

Reinfection is diagnosed by documenting the present cause of bacteriuria as a microorganism different from that responsible for the last infection. In addition, episodes are usually spaced at least 4 to 8 weeks apart, and the patient isasymptomatic after completing each course of antibiotics. Since a urine culture cannot be adequately interpreted without a urinalysis (ie, specific gravity and the presence of pyuria), this test should be done whenever a urine culture is ordered to identify the new organism and to establish its antibiotic susceptibility profile. Short-course therapy for 3 days may be prescribed for each episode. Follow-up visits and urine cultures do not need to be done after each treatment course unless symptoms persist or recur shortly after antibiotics are stopped (ie, within 4 weeks).

Prevention of recurrent infections. Most women with recurrent UTIs have an average of 2-3 episodes per year.[8,12] At this rate of infection, individual episodes of infection can be managed with short-course antibiotic therapy and prophylaxis is not needed.When the number of infection episodes becomes more frequent (ie, a new infection every month or every other month), antibiotic prophylaxis to prevent further reinfections is warranted. In order to clearly establish whether reinfections are related to sexual intercourse, it may be helpful to have women keep a urinary tract infection record book that outlines the onset of infection in relationship to sexual activity. If frequent reinfection episodes are clearly associated with sexual intercourse, antibiotic prophylaxis may be instituted. In addition, women should be instructed to void immediately after intercourse whenever possible. Women who are using a diaphragm and/or spermicide for birth control may also consider changing to an alternative contraceptive method if other measures are not entirely effective in controlling the frequency of infection.

Antibiotic prophylaxis is most easily managed when a single daily dose is taken at the same time every day (Table V), either every morning or at bedtime, depending upon a patient's preference. For women whose reinfections are temporally related to sexual activity, they may elect to take a prophylactic antibiotic dose either just before or following intercourse, but for most patients compliance is harder to maintain using this approach and therefore may not be as effective as continuously taking a single daily dose. A prophylactic antibiotic course is usually maintained for an initial 6-month period in which recurrent UTIs are usually substantially decreased.

Once prophylaxis is stopped, the rate of recurrence needs to be monitored to ensure that new infections are now occurring much less frequently than before prophylaxis was started (ie, decreased to 2-3 new episodes a year).

For women who may be genetically predisposed to recurrent infections with uropathogenic E coli, long-term antibiotic prophylaxis may be the only way to control frequent episodes of new infection, because nothing can change their increased receptor density. It is also important for these women to adopt the preventive measures mentioned earlier to reduce episodes associated with sexual intercourse.