Effective prophylaxis for recurrent urinary tract infections during pregnancy.

Effective prevention of recurrent urinary tract infections (UTIs) and possible acute pyelonephritis is of major importance during pregnancy. During 39 pregnancies, 33 women with a history of recurrent UTIs (and, in some instances, pyelonephritis) received postcoital prophylaxis consisting of a single oral dose of either cephalexin (250 mg) or nitrofurantoin macrocrystals (50 mg). While 130 UTIs occurred during a mean observation period of 7 months before prophylaxis, only a single UTI occurred during pregnancy after prophylaxis; this difference was highly significant. Thus the use of one of these effective regimens is strongly recommended for any pregnant woman with a history of recurrent UTIs. The treatment's effectiveness can be explained by two features of the two antibacterial agents involved: both reach high bactericidal concentrations in the urinary tract and induce no (or minimal) resistance in the introital gram-negative bacterial flora.