When should asymptomatic bacteriuria be treated?

When to Treat Asymptomatic Bacteriuria

Asymptomatic bacteriuria should be treated in only two clinical situations: pregnant women and patients undergoing urologic procedures with anticipated mucosal bleeding. 1, 2 In all other populations, treatment causes more harm than benefit by promoting antimicrobial resistance, increasing adverse drug events, and potentially eliminating protective bacterial strains. 2, 3

Populations Requiring Treatment

Pregnant Women

• Screen all pregnant women with a urine culture at 12–16 weeks' gestation (or at the first prenatal visit) and treat if ≥10⁵ CFU/mL is isolated. 2, 4
• Untreated asymptomatic bacteriuria progresses to pyelonephritis in 20–35% of pregnant women, compared to only 1–4% when treated. 4
• Treatment reduces preterm birth risk from approximately 53 per 1000 to 14 per 1000. 4
• Use a 3–7 day course of targeted antibiotics based on culture susceptibility; nitrofurantoin, beta-lactams (ampicillin, cephalexin), or single-dose fosfomycin trometamol are acceptable options. 1, 2, 4
• Obtain a follow-up urine culture after treatment to confirm clearance and continue periodic screening throughout pregnancy, as recurrence is common. 4

Urologic Procedures with Mucosal Trauma

• Screen with urine culture before any endoscopic urologic procedure that will breach the mucosa and cause bleeding (transurethral resection of prostate/bladder tumor, ureteroscopy with lithotripsy, percutaneous stone surgery). 2, 5
• Untreated bacteriuric patients undergoing these procedures have a bacteremia risk up to 60% and sepsis risk of 6–10%. 2
• Administer targeted antimicrobial therapy 30–60 minutes before the procedure, limit to 1–2 doses, and discontinue immediately after unless an indwelling catheter remains. 2, 6
• If a catheter is left in place post-procedure, continue antibiotics only until catheter removal. 2

Special Consideration: Catheter Removal

• Women with catheter-acquired bacteriuria persisting ≥48 hours after catheter removal may be considered for treatment (weak recommendation). 2, 7
• A 3-day regimen may be sufficient for women ≤65 years without upper tract symptoms. 2

Populations Where Treatment Is NOT Recommended

The following groups should never be screened or treated for asymptomatic bacteriuria, as multiple high-quality studies demonstrate no reduction in symptomatic UTI, mortality, or morbidity: 1, 2, 7

• Premenopausal, non-pregnant women – Treatment does not prevent symptomatic infection and may increase the risk of subsequent UTI by eliminating protective bacterial strains. 2, 7
• Postmenopausal women (community-dwelling or institutionalized) 1, 2
• Diabetic patients (both sexes) – No benefit in symptomatic infection rates, mortality, or diabetic complications. 1, 2
• Elderly patients (community-dwelling or long-term care residents) – Randomized trials showed similar rates of symptomatic UTI and mortality at 9 years, but significantly more adverse drug events and resistant organisms in treated patients. 1, 2
• Patients with spinal cord injury 1, 2
• Renal transplant recipients (beyond the first month post-transplant) 2, 7
• Patients with recurrent UTI history – Treatment is actually harmful in this population. 2
• Patients with dysfunctional or reconstructed lower urinary tracts 1, 2
• Patients before orthopedic arthroplasty surgery 1, 2
• Patients before cardiovascular surgery 1, 2
• Catheterized patients while the catheter remains in place – All catheterized patients develop bacteriuria due to biofilm formation; treatment is futile and does not prevent subsequent symptomatic infection. 2, 7

Critical Diagnostic Pitfalls to Avoid

• Pyuria accompanying asymptomatic bacteriuria is NOT an indication for treatment. 1, 2, 7 The presence or absence of white blood cells in urine does not change management.
• Do not order urine cultures in asymptomatic patients outside the two indicated populations above – the results will not change management and promote unnecessary antibiotic use. 2, 7
• Dipstick urinalysis has poor positive and negative predictive values for bacteriuria in asymptomatic persons and should not trigger treatment. 2, 7
• Do not confuse nonspecific symptoms (delirium, falls, functional decline) in elderly patients with symptomatic UTI – assess for other causes rather than treating bacteriuria. 7

Harms of Unnecessary Treatment

• Adverse drug reactions occur without any offsetting clinical benefit. 2, 7
• Selection pressure for antimicrobial-resistant organisms is a documented consequence of treating asymptomatic bacteriuria. 2, 8, 3
• Increased likelihood of subsequent symptomatic UTI after treatment by eradicating protective bacterial strains that prevent pathogenic colonization. 2, 7, 3
• Five times more days of antibiotic exposure with higher incidence of side effects compared to no treatment. 2

Diagnostic Criteria for Asymptomatic Bacteriuria

• Women: Two consecutive clean-catch voided specimens with the same organism at ≥10⁵ CFU/mL 1, 2, 7
• Men: Single clean-catch voided specimen with ≥10⁵ CFU/mL 1, 2, 7
• Catheterized patients: Single specimen with ≥10² CFU/mL 1, 2, 7
• All diagnoses require complete absence of urinary tract symptoms (dysuria, frequency, urgency, suprapubic pain). 2, 7