In Vitro Activity of Aminopenicillins Combined with Sulbactam, Clavulanic Acid, or Amdinocillin Against Bacteria Isolated from Patients with Complicated Urinary Tract Infections
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 >8 µg/ml). Combination of an aminopenicillin with a β-lactamase inhibitor improved the activity of the aminopenicillin against gram-negative as wellas 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.