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 E. coli and 10 OXA-48 family producing K. pneumoniae Antibiotic concentrations used are achievable in critically ill patients. The combination was synergistic against 7/10 KPC producers and in 9/10 OXA-48 producers. There was no synergy detected in control isolates producing NDM-1.