Assessment of Piperacillin-Tazobactam-Meropenem Synergy against Serine Carbapenemase-Producing Enterobacterales Using Time-Kill Assays.

Synergy between piperacillin-tazobactam and meropenem against KPC-producing Klebsiella pneumoniae was recently demonstrated. We sought to test the combination against a broader range of serine carbapenemase producers. We tested the combination against 10 KPC-producing Escherichia coli and 10 OXA-48 family-producing K. pneumoniae isolates. Antibiotic concentrations used are achievable in critically ill patients. The combination was synergistic against 7 of 10 KPC producers and 9 of 10 OXA-48 producers. There was no synergy detected in control isolates producing NDM-1.