Which antibiotics are appropriate for treating bacteriuria in pregnancy?

Bacteriuria in pregnancy, with or without clinical symptoms, is frequent. If left untreated, it can in 20-30% of cases lead to acute pyelonephritis, which is a serious threat to the mother and fetus, increasing the risk of preterm labour and low birthweight infants. This paper is a review of the literature concerning antibacterial treatment of bacteriuria in pregnancy. It is crucial to ensure that drugs to be used in pregnancy are safe and effective. Established first-line drugs such as ampicillin (pivampicillin) and amoxycillin, and other commonly used treatments such as trimethoprim-sulphamethoxazole, are associated with a high degree of resistance in Escherichia coli, the most common pathogen in the urinary tract. A recent survey of physicians in Denmark, Finland, Norway and Sweden confirms that beta-lactam antibiotics (particularly pivmecillinam) and nitrofurantoin are the drugs of first choice in the treatment of bacteriuria in pregnancy in the Nordic countries. No teratogenic effects have been associated with these agents. In contrast to nitrofurantoin, pivmecillinam is also efficient against pyelonephritis. In spite of resistance in E. coli and possible adverse effects on the fetus, many physicians still prescribe sulphonamides during the first two trimesters of pregnancy.