Consequences for the mother and the newborn of treated and untreated bacteriuria during pregnancy
Asymptomatic bacteriuria in pregnant women does not lead to premature birth, but statistically leads much more often to the development of pyelonephritis, however, the absolute risk of pyelonephritis in case of untreated bacteriuria is low.
Current approaches to the examination and treatment of asymptomatic bacteriuria in pregnant patients are based on studies published over 30 years ago. In a study in the Netherlands, a re-evaluation of the effects on the mother and the newborn of asymptomatic bacteriuria treated and untreated during pregnancy was carried out again.
To achieve this goal, a prospective multicenter cohort study was conducted with an additional randomized controlled trial as part of this project. The study, which was conducted in 8 hospitals and 5 ultrasound diagnostic centers in the Netherlands, examined women aged 18 and over with a single pregnancy for a period of 16 to 22 weeks and with asymptomatic bacteriuria. The survey was carried out using a single dip-test and a double bacteriological study. The diplid test was considered positive if the colony concentration was at least 1 × 105 CFU / ml for a microorganism or if 2 different types of colony were present and at least one type of colony was 1 × 105 CFU / ml.
Women with asymptomatic bacteriuria were considered eligible to participate in a randomized controlled trial comparing nitrofurantoin and placebo. Patients were randomized into a 1: 1 ratio to receive nitrofurantoin 100 mg 2 times daily for 5 days or a placebo. 1 week after the end of treatment, a test with a slide was performed.
During the project, the women, the treating physicians and the researchers did not know the state of the bacteriuria and the treatment group distributed. Women who refused to participate in the study did not receive antibiotics, but the results of bacteriuria were evaluated for analysis in a cohort study. During the work, the results were compared in women with bacteriuria who did not receive treatment and received a placebo, with results in women without bacteriuria and in patients with bacteriuria who received nitrofurantoin. The main outcome parameter evaluated was the development of pyelonephritis with or without premature birth with a gestational age of less than 34 weeks.
For the period from October 11, 2011 to June 10, 2013, 5,621 women were included in the cohort examined; 5132 patients were screened. The final analysis included data from 4283 patients, of whom 248 were asymptomatic bacteriuria, 40 were randomized to the nitrofurantoin group and 45 to the placebo group. Another 163 women with asymptomatic bacteriuria were left untreated.
The proportion of patients who developed pyelonephritis, preterm delivery, or both did not differ between groups of women with bacteriuria who did not receive treatment or a placebo and women without bacteriuria (2.9 % vs 1.9%, a correlated odds ratio of 1.5, 95% CI 0.6-3.5), or between groups of women with bacteriuria treated with nitrofurantoin and women not receiving treatment or receiving a placebo (2.5% vs 2.9%; risk difference -0.4, 95% CI of -3.6 to 9, 4).
Pyelonephritis developed in 5 of 208 women (2.4%) with asymptomatic bacteriuria who did not receive treatment or received a placebo, and in 24 of 4035 women (0.6%) without bacteriuria (report correlated odds of 3.9, 95% CI 1.4-11.4).
Thus, in pregnant women with asymptomatic bacteriuria, this condition does not lead to premature birth. Asymptomatic bacteriuria leads statistically significantly more often to the development of pyelonephritis, but the absolute risk of pyelonephritis in case of untreated bacteriuria is low. The results of the study remind us of the need for routine examination and treatment of pregnant women with asymptomatic bacteriuria.