Asymptomatic bacteriuria treatment is associated with a higher prevalence of antibiotic resistant strains in women with urinary tract infections

Clin Infect Dis. 2015 Dec 1;61(11):1655-61. doi: 10.1093/cid/civ696. Epub 2015 Aug 12.


Background: Women suffering from recurrent urinary tract infections (rUTIs) are routinely treated for asymptomatic bacteriuria (AB), but the consequences of this procedure on antibiotic resistance are not fully known. The aim of this study was to evaluate the impact of AB treatment on antibiotic resistance among women with rUTIs.

Methods: The study population consisted of 2 groups of women who had previously been enrolled in a randomized clinical trial: group A was not treated, and group B was treated. All women were scheduled for follow-up visits every 6 months, or more frequently if symptoms arose. Microbiological evaluation was performed only in symptomatic women. All women were followed up for a mean of 38.8 months to analyze data from urine cultures and antibiograms.

Results: The previous study population consisted of 673 women, but 123 did not attend the entire follow-up period. For the final analysis, 257 of the remaining 550 patients were assigned to group A, and 293 to group B. At the end of follow-up, the difference in recurrence rates was statistically significant (P < .001): 97 (37.7%) in group A versus 204 (69.6%) in group B. Isolated Escherichia coli from group B showed higher resistance to amoxicillin-clavulanic acid (P = .03), trimethoprim-sulfamethoxazole (P = .01), and ciprofloxacin (P = .03) than that from group A.

Conclusions: This study shows that AB treatment is associated with a higher occurrence of antibiotic-resistant bacteria, indicating that AB treatment in women with rUTIs is potentially dangerous.

Keywords: antibiotic resistance; antibiotic stewardship; asymptomatic bacteriuria; urinary tract infection.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Amoxicillin-Potassium Clavulanate Combination / therapeutic use
  • Anti-Bacterial Agents / therapeutic use*
  • Asymptomatic Infections / epidemiology
  • Asymptomatic Infections / therapy
  • Bacteriuria / drug therapy
  • Bacteriuria / epidemiology
  • Drug Resistance, Multiple, Bacterial*
  • Escherichia coli / drug effects*
  • Escherichia coli / isolation & purification
  • Escherichia coli Infections / drug therapy
  • Escherichia coli Infections / microbiology*
  • Female
  • Follow-Up Studies
  • Humans
  • Italy / epidemiology
  • Microbial Sensitivity Tests
  • Middle Aged
  • Prevalence
  • Trimethoprim, Sulfamethoxazole Drug Combination / therapeutic use
  • Urinalysis
  • Urinary Tract Infections / drug therapy
  • Urinary Tract Infections / microbiology*


  • Anti-Bacterial Agents
  • Amoxicillin-Potassium Clavulanate Combination
  • Trimethoprim, Sulfamethoxazole Drug Combination