What is the test of cure for asymptomatic bacteriuria (ASB) in pregnancy?

From the Guidelines

A test of cure is recommended for asymptomatic bacteriuria in pregnancy after completing antibiotic treatment, and it should be performed 1-2 weeks after finishing the antibiotic course by obtaining a clean-catch urine culture, as stated in the guidelines by the Infectious Diseases Society of America 1. This approach is crucial because untreated or persistent asymptomatic bacteriuria can progress to pyelonephritis in 20-40% of pregnant women, which increases risks of preterm birth and low birth weight.

• The duration of antimicrobial therapy should be 3–7 days, as recommended by the guidelines 1.
• Common first-line treatments include nitrofurantoin 100mg twice daily for 5-7 days (avoid in late third trimester), amoxicillin-clavulanate 500/125mg twice daily for 3-7 days, or cephalexin 500mg four times daily for 3-7 days.
• If the follow-up culture remains positive, retreatment with a different antibiotic based on susceptibility testing is necessary.
• Monthly urine cultures should be performed throughout pregnancy for women with a history of bacteriuria to ensure early detection and treatment of recurrences, as periodic screening for recurrent bacteriuria should be undertaken following therapy 1.
• If recurrent bacteriuria is detected, suppressive antibiotic therapy may be needed for the remainder of pregnancy.

From the Research

Test of Cure in Asymptomatic Bacteriuria in Pregnancy

• The test of cure for asymptomatic bacteriuria in pregnancy is typically performed using urine culture, which is the gold standard for diagnosing asymptomatic bacteriuria 2, 3, 4.
• A positive urine culture confirms the presence of asymptomatic bacteriuria, while a negative result effectively rules out the condition 2.
• Other screening tests, such as dipstick urinalysis and microscopic urinalysis, may be used to support the diagnosis, but they are not as sensitive or specific as urine culture 3.
• The choice of antibiotic treatment should be guided by antimicrobial susceptibility testing whenever possible, and nitrofurantoin is often considered the antibiotic of choice for asymptomatic bacteriuria in pregnancy 2, 3.

Duration of Treatment

• The duration of treatment for asymptomatic bacteriuria in pregnancy is typically 7 days, although some studies suggest that a shorter course of treatment (e.g., 1-3 days) may be effective in some cases 5, 6.
• A 7-day regimen of antibiotics has been shown to result in a better microbiological cure rate compared to a 1-day regimen, although there may be no difference in important clinical outcomes such as preterm delivery or pyelonephritis 5.
• The choice of treatment duration should be individualized based on the patient's specific circumstances and the results of antimicrobial susceptibility testing 5, 6.

Screening and Treatment Recommendations

• Screening for asymptomatic bacteriuria is a standard of obstetrical care and is recommended for all pregnant women 4, 6.
• Treatment of asymptomatic bacteriuria is associated with a decrease in the incidence of pyelonephritis and preterm delivery, although the strength of this association is not well established 4.
• The treatment of asymptomatic bacteriuria should be guided by the results of urine culture and antimicrobial susceptibility testing, and should be individualized based on the patient's specific circumstances 2, 3, 4, 6.