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Abstract
Introduction. The therapeutic options to treat Acinetobacter baumannii infections are very limited.
Aim. Our aim was to evaluate the activity of sulbactam combined directly with avibactam or the ampicillin-sulbactam/ceftazidime-avibactam combination against extensively drug-resistant A. baumannii isolates.
Methodology. Extensively drug-resistant A. baumannii isolates (n=127) collected at several South American hospitals were studied. Synergy with the sulbactam/avibactam combination was assessed in all isolates using the agar dilution method. Avibactam was used at a fixed concentration of 4 mg l−1. A disc diffusion synergy test was also performed. Synergy by a time-kill experiment was performed in a selected isolate.
Results. Synergy with sulbactam/avibactam was demonstrated in 124 isolates and it showed MIC values ≤4 mg l−1. This synergy was not detected in the three New Delhi metallo-β-lactamase-harbouring isolates. Similar results were observed with the disc diffusion synergy test of ampicillin-sulbactam/ceftazidime-avibactam. In the time-kill experiments, sulbactam/avibactam showed a rapid synergistic and bactericidal activity in ampicillin-sulbactam-resistant isolates.
Conclusions. This study demonstrated that the sulbactam/avibactam combination displayed synergistic activity against A. baumannii isolates. This synergy was observed when both inhibitors were also used as part of the commercially available combinations: ampicillin-sulbactam and ceftazidime-avibactam.
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Funding
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Secretaria de Ciencia y Tecnica, Universidad de Buenos Aires
(Award UBACyT 20020130100167BA)
- Principle Award Recipient: Angela Famiglietti