From the Guidelines
A test of cure is recommended for asymptomatic bacteriuria in pregnancy after completing antibiotic treatment, as it ensures complete bacterial clearance and prevents potential complications such as pyelonephritis. This follow-up urine culture should be performed 1-2 weeks after completing the antibiotic course to confirm eradication of bacteria, as suggested by the Infectious Diseases Society of America guidelines 1. If the test of cure remains positive, retreatment with a different antibiotic based on susceptibility testing is necessary. Common first-line treatments include nitrofurantoin 100 mg orally twice daily for 5-7 days, amoxicillin-clavulanate 500/125 mg orally twice daily for 3-7 days, or cephalexin 500 mg orally four times daily for 3-7 days, with the duration of antimicrobial therapy being 3–7 days as recommended by the guidelines 1.
Key Considerations
- The diagnosis of asymptomatic bacteriuria should be based on results of culture of a urine specimen collected in a manner that minimizes contamination, with bacteriuria defined as 2 consecutive voided urine specimens with isolation of the same bacterial strain in quantitative counts ≥10^5 cfu/mL for asymptomatic women 1.
- Pregnant women should be screened for bacteriuria by urine culture at least once in early pregnancy, and they should be treated if the results are positive, with periodic screening for recurrent bacteriuria undertaken following therapy 1.
- After successful treatment, monthly urine cultures should be performed throughout the remainder of pregnancy to monitor for recurrence, as untreated asymptomatic bacteriuria can progress to pyelonephritis in 20-40% of pregnant women, increasing risks of preterm birth and low birth weight.
Treatment and Follow-Up
- The choice of antibiotic should be based on susceptibility testing and local resistance patterns.
- The test of cure ensures complete bacterial clearance, as pregnancy-related physiological changes like urinary stasis and decreased immune function can make infections more persistent and difficult to eradicate.
- Regular follow-up with urine cultures is crucial to prevent complications and ensure the best possible outcomes for both the mother and the fetus.
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 low birth weight 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.
Importance of Screening and Treatment
- Screening for asymptomatic bacteriuria is a standard of obstetrical care and is included in most antenatal guidelines 4.
- Treatment of asymptomatic bacteriuria has been shown to decrease the incidence of pyelonephritis and may also reduce the risk of preterm delivery or low birth weight, although the evidence for this is not as strong 4, 6.
- Screening and treatment of asymptomatic bacteriuria is only recommended for pregnant women and patients who are candidates for urological procedures breaching the mucosa, as unnecessary treatment can be harmful 6.