Acute pyelonephritis in pregnancy.

: There were 107 episodes of pyelonephritis associated with pregnancy or the early puerperium occurring in 103 gravidas investigated retrospectively for information concerning prematurity, low birthweight, and antibiotic susceptibility patterns in the recovered microorganisms. No difference was found in the incidence of prematurity on low birthweight between that group and a control group of gravidas from the same population. Members of the Enterobacteriaceae genus were the most common bacterial isolates from the urine, with a large portion of E. coli being resistant to both ampicillin (33%) and cephalothin (13%). Treated pyelonephritis associated with pregnancy does not appear to predispose to prematurity or low birthweight in this population. Also, initial therapy with a first-generation cephalosporin may no longer be appropriate, because a significant number of isolates (11%) were resistant to cephalothin.