Ampicillin-resistant Escherichia coli in gestational pyelonephritis: Increased occurrence and association with the colonization factor Dr adhesin

The pattern of ampicillin resistance and possible association with virulenc e factors of 78 Escherichia coli isolates taken from 78 pregnant women with pyelonephritis were evaluated. The current incidence of ampicillin resista nce among pyelonephritis isolates (46%) was significantly higher than that reported in 1985 (22%). Resistance was found more frequently during the fir st (60%) and third (53%) trimesters than during the second trimester (33%). Of all dra(+) E. coli isolates, 75% were ampicillin resistant, whereas dra (+) isolates of O75 serotype E. coli accounted for 87% of ampicillin-resist ant strains. The significant increase of ampicillin resistance among gestat ional pyelonephritis E. coli and the association with the dra gene cluster encoding colonization and invasive capacity may warrant further study invol ving obstetric and neonate wards, with the latter being at the higher risk for potential problems.