Evidence Summary

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In older people with bacteria in their urine and no symptoms, antibiotics may not prevent development of urinary tract infection

Koves B, Cai T, Veeratterapillay R, et al. Benefits and Harms of Treatment of Asymptomatic Bacteriuria: A Systematic Review and Meta-analysis by the European Association of Urology Urological Infection Guidelines Panel. Eur Urol. 2017;72:865-8.

Review question

In people with bacteria in their urine and no symptoms (asymptomatic bacteriuria), does treatment improve outcomes?


People can have bacteria in their urine without any obvious symptoms of infection, such as pain with urination, frequent need to urinate, low back pain, confusion, or fever. Women, older adults, and people who have had urinary tract surgery are more likely to get asymptomatic bacteriuria. However, we don’t know if antibiotics may be helpful to treat some people who are at higher risk for getting a urinary tract infection.

How the review was done

The researchers did a systematic review of studies available up to November 2016. They looked at studies of different kinds of people with asymptomatic bacteriuria. For this summary, we will focus on the 3 randomized controlled trials that assessed treatments to prevent urinary tract infections in 210 older people living in nursing homes or other institutions.

The key features of the 3 studies of older people living in nursing homes or institutions were:

  • people were older than 18 years of age and had asymptomatic bacteriuria;
  • treatments included different kinds of antibiotics;
  • treatments were compared with placebo or no treatment; and
  • people were followed for 6 to 11 months.

All studies were considered to be very low quality, which means that new studies might show different results.

What the researchers found

Compared with placebo or no treatment, antibiotics did not reduce development of new symptomatic urinary tract infections in older people living in institutional settings.


In older people who live in nursing homes or other institutions and have bacteria in their urine, antibiotics may not prevent development of symptomatic urinary tract infections. Overall, evidence was of very low quality.

Antibiotics vs control* in older people living in nursing homes or other institutions who have bacteria in their urine


Number of trials (people)

Rate of events with antibiotics†

Rate of events with control

Absolute effect of antibiotics

Symptomatic urinary tract infections

3 trials (210 people)



No difference in effect‡

*Placebo or no treatment.

†The event rate in the antibiotics group was weighted. This means it may be a little different than you would expect if you just divided number of people who had an event with the number of people who were treated.

‡Although the rates for the 2 groups look a little different, the differences were not statistically significant. This means that the differences could simply be due to chance rather than due to different treatments.


A harmless, inactive, and simulated treatment.
Randomized controlled trials
Studies where people are assigned to one of the treatments purely by chance.
Systematic review
A comprehensive evaluation of the available research evidence on a particular topic.

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