Three Versus Seven-Day Treatment of Asymptomatic Bacteriuria in Pregnant Women: A Pilot Investigation

To compare 3-day vs 7-day antimicrobial treatment for asymptomatic bacteriuria in pregnant women in a pilot study.

Pregnant women with asymptomatic bacteriuria (100,000 cfu/mL) were randomized to 3-day or 7-day nitrofurantoin treatment. Exclusion criteria included symptomatic bacteriuria at enrollment, previously treated bacteriuria in the current pregnancy, underlying renal disorders, antibiotic use within one week prior to initial culture or treatment, bacterial resistance to nitrofurantoin, or other contraindications to nitrofurantoin. Urine test of cure (TOC) was performed 2-4 weeks after initiation of treatment. Subjects with persistent bacteriuria received an additional 7-day treatment course with an antimicrobial agent based on uropathogen sensitivities and selected at the physician’s discretion. Following delivery, antenatal, perinatal, and neonatal data were reviewed. Statistical analyses were performed using t-test, Chisquare, and Fisher exact where appropriate. Analysis was based on intent-to-treat.

Forty-four of 60 patients had complete prenatal and delivery records. Twenty-four patients (54.5%) were randomized to 3-day treatment and 20 patients (45.5%) to 7-day treatment. Six (25%) patients in the 3-day group had persistent bacteriuria at TOC, compared to 2 (10%) patients in the 7-day group (p=0.19). There were no statistical differences between the groups in maternal age, gestational age at enrollment, mode of delivery, birth weight, NICU admissions, or the incidence of recurrent urinary tract infections or pyelonephritis.

Based on our small sample group, 3-day nitrofurantoin treatment had statistically comparable outcomes to 7- day treatment for asymptomatic bacteriuria in pregnant patients, yet 3-day-treated women were 2.5 times more likely to have persistent bacteriuria than 7-day-treated women. The possibility of a beta error exists. In light of recent data which indicates that 1-day nitrofurantoin therapy is less effective than 7-day treatment in pregnant women, we recommend 7-day treatment for ASB.