From the Guidelines
Treatment of asymptomatic bacteriuria (ASB) is recommended only in pregnant women and patients undergoing urologic procedures with mucosal bleeding. In pregnant women, treatment reduces the risk of pyelonephritis, preterm delivery, and low birth weight infants, as supported by the Infectious Diseases Society of America guidelines 1 and further emphasized by the benefits of screening and treatment programs in pregnant women 1. For pregnant women, preferred antibiotics include nitrofurantoin 100 mg twice daily for 5 days, amoxicillin 500 mg three times daily for 3-7 days, or cephalexin 500 mg four times daily for 3-7 days.
Key Considerations for Treatment
- For urologic procedures, a single dose of antibiotics just before the procedure is sufficient, typically using fluoroquinolones like ciprofloxacin 500 mg or trimethoprim-sulfamethoxazole (TMP-SMX) 160/800 mg, as recommended by the European Association of Urology guidelines 1.
- ASB should not be treated in non-pregnant women, elderly patients, diabetics, or those with indwelling catheters as treatment provides no benefit and increases antibiotic resistance risk.
- Before initiating treatment, a urine culture should confirm bacteriuria (>100,000 CFU/mL) in the absence of symptoms.
Rationale for Selective Treatment
The rationale for selective treatment is that bacteria colonizing the urinary tract without causing symptoms generally don't require elimination, and unnecessary antibiotic use contributes to antimicrobial resistance while exposing patients to potential medication side effects. This approach is supported by the most recent guidelines, which prioritize the reduction of unnecessary antibiotic use 1.
Conditions Not Requiring Treatment
Conditions where screening or treatment of ASB is not recommended include:
- Women without risk factors
- Patients with well-regulated diabetes mellitus
- Postmenopausal women
- Elderly institutionalized patients
- Patients with a dysfunctional and/or reconstructed lower urinary tract
- Patients with a renal transplant
- Patients before arthroplasty surgery
- Patients with recurrent urinary tract infections, as outlined in the European Association of Urology guidelines 1.
From the Research
Treatment of Asymptomatic Bacteriuria
The treatment of asymptomatic bacteriuria (ASB) is recommended in specific patient groups, including:
- Pregnant women: Treatment of ASB in pregnant women has been shown to decrease the risk of symptomatic urinary tract infections (UTIs), low birth weight, and preterm delivery 2, 3, 4.
- Patients undergoing urologic procedures: Treatment of ASB prior to transurethral resection surgery has been shown to reduce the risk of postoperative UTIs 3.
- Patients with certain medical conditions: However, treatment of ASB is not recommended for patients with diabetes, neutropenia, spinal cord injuries, indwelling urinary catheters, and other conditions, as it has not been shown to improve clinical outcomes 2, 5, 4.
Preferred Antibiotics
The preferred antibiotics for the treatment of ASB include:
- Nitrofurantoin: This antibiotic has been shown to be effective in treating ASB and has minimal collateral damage and resistance 6.
- Fosfomycin: This antibiotic is also effective in treating ASB and has minimal collateral damage and resistance 6.
- Trimethoprim-sulfamethoxazole: This antibiotic can be used to treat ASB, but its use should be guided by local resistance patterns 6.
- Beta-lactams: These antibiotics can be used to treat ASB in pregnancy, but their use should be guided by local resistance patterns 6.
Patient Groups Who Should Not Be Treated
The following patient groups should not be treated for ASB:
- Pediatric patients
- Healthy nonpregnant women
- Older patients in the inpatient or outpatient setting
- Diabetic patients
- Patients with an indwelling urethral catheter
- Patients with impaired voiding following spinal cord injury
- Patients undergoing nonurologic surgeries
- Nonrenal solid-organ transplant recipients
- Renal transplant recipients beyond 1 month posttransplant 2.