Which high‑risk groups require treatment of asymptomatic bacteriuria and what are the recommended first‑line antimicrobial regimens for each (pregnant women, patients undergoing urologic or gynecologic procedures that breach the urinary mucosa, neutropenic patients or those with hematologic malignancy, and early renal‑transplant recipients)?

Treatment of Asymptomatic Bacteriuria

Asymptomatic bacteriuria should be treated in only two populations: pregnant women and patients undergoing urologic procedures that breach the urinary mucosa. 1, 2 In all other patient groups, treatment causes more harm than benefit through adverse drug events, selection of resistant organisms, and increased risk of subsequent symptomatic infections. 1, 2

High-Risk Groups Requiring Treatment

Pregnant Women

Screen all pregnant women with urine culture at 12-16 weeks gestation (or first prenatal visit) and treat confirmed bacteriuria with a 3-7 day course of targeted antibiotics. 1, 2

• Untreated asymptomatic bacteriuria in pregnancy carries a 40% risk of progression to pyelonephritis, which is associated with preterm delivery and low birth weight 1
• Diagnostic threshold: ≥10⁵ CFU/mL on a single voided specimen, or ≥10⁴ CFU/mL for Group B Streptococcus 3
• First-line antimicrobial regimens:
  • Nitrofurantoin (3-7 days) 2
  • Ampicillin (3-7 days) 2
  • Cephalexin (3-7 days) 2
  • Fosfomycin trometamol (single 3-gram dose) 1, 2
• Perform periodic screening for recurrent bacteriuria following initial treatment 1, 2

Patients Undergoing Urologic Procedures with Mucosal Bleeding

Screen with urine culture before any endoscopic urologic procedure anticipated to cause mucosal trauma, and administer targeted antimicrobial prophylaxis 30-60 minutes before the procedure. 1, 2

• Procedures requiring screening include: transurethral resection of prostate (TURP), transurethral resection of bladder tumor (TURBT), ureteroscopy with lithotripsy, percutaneous nephrolithotomy, and any procedure using high-pressure irrigants 1
• Untreated bacteriuria in these patients results in bacteremia in up to 60% and sepsis in 6-10% 2
• Antimicrobial prophylaxis protocol:
  • Obtain urine culture results before the procedure to guide targeted therapy rather than empiric coverage 2
  • Initiate antimicrobials 30-60 minutes pre-procedure 1, 2
  • Limit to 1-2 doses only 2
  • Discontinue immediately after the procedure if no indwelling catheter remains 1, 2
  • If an indwelling catheter is left in place post-procedure, continue antibiotics only until catheter removal 1
• Select the antimicrobial agent based on prior urine culture results and local antibiogram 1

Gynecologic Procedures with Mucosal Breach

By extrapolation from urologic data, screening and treatment are reasonable for gynecologic procedures anticipated to cause significant mucosal trauma, though direct evidence is lacking. 2

• Use the same antimicrobial prophylaxis protocol as for urologic procedures 2

Populations Where Treatment Is NOT Recommended

The following groups should never be screened or treated for asymptomatic bacteriuria, as treatment provides no clinical benefit and causes harm: 1, 2

Non-Pregnant Women (All Ages)

• Premenopausal, non-pregnant women: Grade A-I (strong) recommendation against treatment 1, 2
• Postmenopausal women (community-dwelling or institutionalized): Grade A-I recommendation against treatment 1, 2
• Treatment does not reduce subsequent symptomatic UTI rates and may increase reinfection risk with resistant organisms 2

Diabetic Patients

• Both men and women with well-controlled diabetes: Grade A-I recommendation against treatment 1, 2
• Treatment does not prevent diabetic complications, reduce infection rates, or improve mortality 2

Elderly Patients

• Community-dwelling older adults: Grade A-I recommendation against treatment 1, 2
• Long-term care facility residents: Grade A-I recommendation against treatment 1, 2
• Randomized trials show similar rates of symptomatic UTI and mortality at 9 years, but significantly more adverse drug events and resistant organisms in treated patients 2

Catheterized Patients

• Patients with indwelling urinary catheters (short-term <30 days or long-term): Grade A-I recommendation against treatment while catheter remains in place 1, 2, 3
• All catheterized patients eventually develop bacteriuria due to biofilm formation; treatment is futile 2
• Exception: Asymptomatic women with catheter-acquired bacteriuria persisting ≥48 hours after catheter removal may be considered for treatment (weak recommendation) 1, 2

Spinal Cord Injury Patients

• Grade A-I recommendation against screening or treatment 1, 2
• Studies show 78% have positive cultures but minimal symptomatic episodes, all responding promptly when treated 2

Renal Transplant Recipients

• Beyond 1 month post-transplant: Grade A-I recommendation against treatment 1, 3
• Recent studies show no association between asymptomatic bacteriuria and graft survival 1
• Insufficient evidence to recommend for or against screening within the first month post-transplant 3

Patients Undergoing Non-Urologic Surgery

• Orthopedic arthroplasty: Strong recommendation against screening/treatment 1, 2
• Cardiovascular surgery: Weak recommendation against screening/treatment 1
• Non-urologic elective surgery: Strong recommendation against screening/treatment 2

Other Populations Not Requiring Treatment

• Patients with dysfunctional or reconstructed lower urinary tracts 1, 2
• Patients with recurrent UTI history (treatment shown to be harmful) 1, 2
• Neutropenic patients (insufficient evidence for routine treatment) 3

Diagnostic Criteria for Asymptomatic Bacteriuria

Diagnosis requires complete absence of urinary symptoms (no dysuria, frequency, urgency, suprapubic pain, fever, or flank pain). 2

• Women: Two consecutive clean-catch voided specimens with the same organism at ≥10⁵ CFU/mL 2, 3
• Men: Single clean-catch voided specimen with ≥10⁵ CFU/mL of a single organism 2, 3
• Catheterized patients: Single specimen with ≥10² CFU/mL 2, 3
• Pregnant women: ≥10⁴ CFU/mL of Group B Streptococcus is significant 3

Critical Pitfalls to Avoid

Pyuria Does Not Indicate Need for Treatment

The presence of pyuria (≥5 WBC/hpf) accompanying asymptomatic bacteriuria is NOT an indication for antimicrobial treatment. 1, 2, 4

• Grade A-I (strong) recommendation with moderate-quality evidence 2, 4
• Pyuria without symptoms does not distinguish colonization from infection 4

Do Not Order Urine Cultures in Asymptomatic Patients

• Urine cultures should not be obtained in asymptomatic individuals, as results do not change management and promote unnecessary antibiotic use 2
• Positive dipstick urinalysis has poor predictive value for bacteriuria in asymptomatic persons and should not trigger treatment 2

Harms of Unnecessary Treatment

• Five-fold increase in antibiotic exposure and significantly more adverse drug events compared to no treatment 2
• Selection of antimicrobial-resistant organisms with increased risk of reinfection by resistant strains 2
• Disruption of normal microbiome 2
• Increased likelihood of subsequent symptomatic UTI after treatment 2
• No improvement in mortality, renal complications, or progression of chronic kidney disease in any population except the two high-risk groups 2

Special Considerations for Neutropenic Patients

There is insufficient evidence to recommend for or against routine screening and treatment of asymptomatic bacteriuria in neutropenic patients or those with hematologic malignancy. 3

• Antifungal prophylaxis (not treatment of asymptomatic funguria) should be given to neutropenic patients undergoing specific high-risk procedures: resective/enucleative/ablative outlet procedures, TURBT, ureteroscopy, PCNL, or procedures with high-pressure irrigants 1
• In the absence of neutropenia, nephrostomy exchanges and ureteral stenting do not require antifungal prophylaxis for asymptomatic funguria 1