Asymptomatic Bacteriuria

[Clin Infect Dis 2005; 40:643-54]

Definitions:

- Asymptomatic bacteriuria (ASB) is a colonization state and does NOT indicate an infection that requires treatment. Pyuria is very common in patients with asymptomatic bacteriuria and is also NOT an indication for antibiotic treatment.

• asymptomatic females - two consecutive voided urine cultures with ≥ 10⁸ cfu/L of same organism +/- pyuria.

• asymptomatic males - one voided urine culture with ≥ 10⁸ cfu/L of ≥ 1 organism +/- pyuria.

• catheterized patients - catheter urine culture with ≥10⁵ cfu/L of ≥ 1 organism +/- pyuria and no symptoms of UTI.

Incidence of asymptomatic bacteriuria:

• young adults: 1-3%

• >65 years old: 20% females, 10% males

• >80 years old: 50% females, 30% males

• catheterized:

  • intermittent: 38-58%

  • short-term (< 30 days) indwelling: 9-23%

  • long-term (≥ 30 days) indwelling: 100%

Prevalence:

- Hospital > nursing home > community

Associated laboratory findings:

- Routine screening cultures not recommended, unless prior to GU surgery or pregnant. NB: cloudy/foul smelling urine alone is not an indication for urine culture.

- Up to 90% of elderly patients with asymptomatic bacteriuria have pyuria, hence pyuria is not a valid diagnostic criterion for UTI in this patient population; clinical correlation required.

Antibiotic therapy:

- NO evidence that antibiotic therapy of asymptomatic bacteriuria decreases symptomatic UTI.

- NO evidence that antibiotic therapy of asymptomatic bacteriuria is of any benefit EXCEPT:

• prior to genitourinary (GU) procedures in which mucosal bleeding/ trauma is expected, or

• in pregnancy.

- Inappropriate treatment of ASB is a significant contributor to antimicrobial overuse, antimicrobial resistance, and adverse drug effects including Clostridioides (Clostridium) difficile infection.

- Antibiotic therapy of asymptomatic bacteriuria is specifically NOT recommended:

• young women with recurrent UTI as it:

  • increases risk of recurrent UTI

  • increases risk of multi-drug resistant E. coli [Clin Infect Dis 2012;55:771-7]

• renal transplant patients

• diabetic patients

• prior to minor urologic procedures (no mucosal bleeding)

• prior to orthopedic surgery

• prior to catheter removal

• patients with long term catheterization

• patients with spinal cord injury.

- Asymptomatic bacteriuria is NOT associated with incontinence, hypertension, or decreased renal function in the elderly.