Interaction of sulbactam, clavulanic acid and tazobactam with penicillin-binding proteins of imipenem-resistant and -susceptible<i>acinetobacter baumannii</i>

Abstract

We have encountered clinical isolates of Acinetobacter baumannii which are resistant to all available antibiotics used in hospitals except for polymyxin B and the beta-lactamase inhibitor, sulbactam. To investigate the mechanisms of this unique activity, affinities of sulbactam and other beta-lactamase inhibitors for penicillin binding proteins were compared using imipenem-resistant and imipenem-sensitive isolates. The results of competition binding experiments indicate that all three beta-lactamase inhibitors bound to imipenem-susceptible Acinetobacter. Binding of sulbactam was greater than that of tazobactam and not detected with clavulanic acid to penicillin binding proteins of the imipenem-resistant strain of Acinetobacter.