Synergistic antibacterial effects of analgesics and antibiotics against Staphylococcus aureus

Abstract The local use of analgesics and antibiotics is common during the treatment of periprosthetic joint infection (PJI). The effect of non-antimicrobial 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 PJI. We identified that bupivacaine/lidocaine and ketorolac/gentamicin combinations yielded FIC indices bellow 0.4 – indicative of synergistic antibacterial effect. Time-kill curves were used for in-depth characterization of the synergy, and the obtained results demonstrated pronounces synergistic effects of bupivacaine/lidocaine and ketorolac/gentamicin combinations against MSSA.