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Updated: Dec 28, 2025

Antimicrobial Synergy Testing by the Inkjet Printer-assisted Automated Checkerboard Array and the Manual Time-kill Method
Published on: April 18, 2019
Synergistic antibacterial effects of analgesics and antibiotics against Staphylococcus aureus
Dmitry Gil1, Kathryn Daffinee2, Renee Friedman3
1Harris Orthopaedic Laboratory, Massachusetts General Hospital, Boston, MA; Department of Orthopaedic Surgery, Harvard Medical School, Harvard University, Boston, MA.
Abstract:
The local use of analgesics and antibiotics is common during the treatment of periprosthetic joint infection (PJI). The effect of nonantimicrobial drugs on antibacterial activity is underappreciated in clinical practice. This study focuses on the novel assessment of the combined antibacterial effects of commonly used analgesics and antibiotics against methicillin-sensitive Staphylococcus aureus (MSSA)-pathogen associated with most PJIs. We identified that bupivacaine/lidocaine and ketorolac/gentamicin combinations yielded fractional inhibitory concentration indices below 0.4, indicative of synergistic antibacterial effect. Time-kill curves were used for in-depth characterization of the synergy, and the obtained results demonstrated pronounced synergistic effects of bupivacaine/lidocaine and ketorolac/gentamicin combinations against MSSA.
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