What is the management approach for asymptomatic bacteriuria (ASB)?

Management of Asymptomatic Bacteriuria

Asymptomatic bacteriuria (ASB) should NOT be screened for or treated in most patient populations, with only two specific exceptions: pregnant women and patients undergoing invasive urologic procedures with mucosal bleeding. 1, 2

Definition and Prevalence

• ASB is defined as the presence of ≥10^5 CFU/mL of bacteria in urine without signs or symptoms of urinary tract infection 1, 3
• For women, two consecutive specimens with the same organism at ≥10^5 CFU/mL are required for diagnosis 3
• For men, a single specimen with ≥10^5 CFU/mL is sufficient for diagnosis 3
• Prevalence varies by population: rare in young healthy individuals, 3.6-19% in community-dwelling older men, 15-50% in long-term care facilities 4, 5

Populations Where Treatment is NOT Recommended

The Infectious Diseases Society of America (IDSA) strongly recommends AGAINST screening for or treating ASB in the following populations:

• Healthy premenopausal, non-pregnant women 1
• Healthy postmenopausal women 1
• Patients with diabetes 1
• Older, community-dwelling persons who are functionally impaired 1
• Older persons resident in long-term care facilities 1
• Patients with spinal cord injuries 1
• Patients with short-term (<30 days) indwelling urethral catheters 1
• Patients with long-term indwelling catheters 1
• Patients with renal transplants who have had surgery >1 month prior 1
• Infants and children 1
• Patients with implanted urological devices 1

Populations Where Treatment IS Recommended

1. Pregnant Women:

   • Screen for and treat ASB in pregnant women 1
   • Suggested screening: urine culture at one of the initial prenatal visits early in pregnancy 1
   • Treatment duration: 4-7 days of antimicrobial therapy rather than shorter duration 1
   • The shortest effective course should be used based on the antimicrobial selected 1

2. Patients Undergoing Urologic Procedures:

   • For patients undergoing endoscopic urologic procedures with risk of mucosal bleeding, obtain urine culture prior to the procedure 1
   • Provide targeted antimicrobial therapy based on culture results rather than empiric therapy 1, 4
   • Short-course treatment (1-2 doses) is preferred over prolonged therapy 1, 4
   • Initiate antibiotics 30-60 minutes before the procedure 4

Special Considerations

• Older Adults with Delirium: In older patients with functional/cognitive impairment who develop delirium without local genitourinary symptoms or other systemic signs of infection, assess for other causes and observe carefully rather than immediately treating bacteriuria 1

• Catheter Removal: No clear recommendation exists for screening or treating ASB at the time of catheter removal, as evidence is insufficient 1

Rationale for Not Treating ASB

• Treatment of ASB in populations without clear benefit leads to:
  • Increased risk of antimicrobial resistance 1, 5
  • Higher risk of Clostridioides difficile infection 1, 5
  • Adverse drug effects 1, 5
  • Reinfection with organisms of increased antimicrobial resistance 6
  • Increased healthcare costs 5

Common Pitfalls to Avoid

• Do not treat ASB based on the presence of pyuria alone - pyuria accompanying ASB is not an indication for antimicrobial treatment 4
• Do not screen for ASB in populations where treatment is not recommended 2, 5
• Do not treat based on colony count alone without considering clinical presentation 7
• Do not treat multiple organisms in urine cultures, which often indicate contamination rather than infection 7
• Do not confuse nonspecific symptoms (like fatigue or mild confusion in the elderly) with UTI symptoms 1

Educational Interventions

• Educational interventions focused on risk factors for inappropriate treatment (female gender, absence of catheter, bacteriuria vs. candiduria, pyuria, positive nitrites) have been shown to reduce unnecessary antibiotic use for ASB 8