In vitro activity of aminopenicillins combined with sulbactam, clavulanic acid, or amdinocillin against bacteria isolated from patients with complicated urinary tract infections.

Abstract

The minimal inhibitory concentrations (MICs) of ampicillin, sulbactam/ampicillin, clavulanic acid/amoxicillin, and amdinocillin/ampicillin were determined for 400 bacteria isolated from the urine of 400 urologic inpatients with complicated and/or hospital-acquired urinary tract infections (UTIs). The spectrum of isolates consisted of about one-third each of Escherichia coli, other gram-negative strains, and gram-positive strains. About one-third of all isolates were resistant to ampicillin (MICs greater than 8 micrograms/ml). Combination of an aminopenicillin with a beta-lactamase inhibitor improved the activity of the aminopenicillin against gram-negative as well as gram-positive strains. The combination of ampicillin with amdinocillin improved the activity of ampicillin against gram-negative strains only. If the total antibacterial spectrum is considered, the improvements in activity provided by the three combinations were quite similar.