Should asymptomatic bacteriuria (ASB) be treated?

Treatment of Asymptomatic Bacteriuria: When to Treat and When to Avoid

Asymptomatic bacteriuria (ASB) should generally NOT be treated with antibiotics except in pregnant women and patients undergoing invasive urologic procedures. 1

Definition and Prevalence

• Asymptomatic bacteriuria is defined as isolation of a specified quantitative count of bacteria in an appropriately collected urine specimen from a person without symptoms or signs referable to urinary infection 1
• Prevalence varies by population:
  • Healthy premenopausal women: 1-5% 1
  • Pregnant women: 2-9.5% 1
  • Diabetic women: 10.8-16% 1
  • Elderly in long-term care: 25-50% in women, 15-50% in men 1
  • Patients with indwelling catheters: 100% with long-term use 1

Populations Where Treatment is NOT Recommended

Healthy Non-Pregnant Women

• Strong recommendation against screening for or treating ASB in healthy premenopausal or postmenopausal women 1
• Treatment provides no benefit for reducing symptomatic infections and may actually increase risk of subsequent symptomatic UTI 1
• Some evidence suggests persistent ASB may protect against symptomatic UTI 1

Diabetic Patients

• Strong recommendation against screening for or treating ASB in patients with diabetes 1
• No evidence of benefit for reducing complications or improving outcomes 1
• Recommendation applies to both women and men with diabetes 1

Older Adults

• Strong recommendation against screening for or treating ASB in elderly persons living in the community or in long-term care facilities 1
• Treatment does not reduce morbidity or mortality and increases risk of adverse drug effects and antimicrobial resistance 1
• Even in cases of delirium or falls in elderly patients with ASB, assessment for other causes is recommended rather than antimicrobial treatment 1

Patients with Indwelling Catheters

• Strong recommendation against screening for or treating ASB in patients with short-term (<30 days) or long-term indwelling catheters 1
• Treatment while catheter remains in place does not reduce complications 1

Other Populations Where Treatment is Not Recommended

• Renal transplant recipients >1 month post-transplant 1
• Patients with spinal cord injury 1
• Patients undergoing elective non-urologic surgery 1
• Patients with implanted urologic devices 1

Populations Where Treatment IS Recommended

Pregnant Women

• Strong recommendation for screening and treating ASB in pregnant women 1
• Untreated ASB in pregnancy increases risk of:
  • Pyelonephritis (progression from 20-35% to 1-4% with treatment) 1
  • Preterm birth 1
  • Low birth weight 1, 2
• Screening recommendation: Urine culture at one of the initial prenatal visits 1
• Treatment recommendation: 4-7 days of antimicrobial therapy 1
• Note: A recent Dutch study suggested non-treatment may be acceptable in selected low-risk women, but further evaluation in other populations is needed 1

Patients Undergoing Urologic Procedures

• Strong recommendation for screening and treating ASB prior to urologic procedures associated with mucosal trauma 1
• Examples include transurethral surgery of prostate or bladder, ureteroscopy, percutaneous stone surgery 1
• Treatment reduces risk of post-procedure bacteremia and sepsis 1
• Recommendation: Obtain urine culture prior to procedure and provide targeted antimicrobial therapy rather than empiric treatment 1
• Short course (1-2 doses) initiated 30-60 minutes before procedure is suggested 1

Clinical Pitfalls and Considerations

• Overtreatment of ASB is common and harmful, leading to:

  • Increased antimicrobial resistance 1, 3
  • Risk of Clostridioides difficile infection 1
  • Adverse drug effects 3, 4
  • Unnecessary healthcare costs 4

• Do not screen for ASB in populations where treatment is not indicated - testing leads to unnecessary treatment 1, 3

• Do not mistake cloudy or malodorous urine as an indication for antibiotics in the absence of symptoms - these are not reliable indicators of infection requiring treatment 1

• Special considerations for specific populations:

  • In patients with spinal cord injury, symptoms of UTI may differ from classic genitourinary symptoms 1
  • For pregnant women, the optimal antimicrobial should be guided by susceptibility testing when possible 5
  • In elderly patients with cognitive impairment, look for other causes of mental status changes before attributing to UTI 1

By following these evidence-based recommendations, clinicians can avoid unnecessary antibiotic use while ensuring appropriate treatment for populations that truly benefit from ASB management.