Novel synergistic antibacterial activity of meloxicam-curcumin and diclofenac-curcumin combinations against methicillin-sensitive S. aureus and E. faecium

Abstract Background Some nonsteroidal anti-inflammatory drugs (NSAIDs) have been shown to have antibacterial activities in different experimental settings. In the current study, the antibacterial activities of meloxicam and diclofenac were evaluated when combined with curcumin, a polyphenolic compound, against clinically relevant bacteria. The aim was to determine whether these combinations could provide a novel, synergistic approach to combat pathogenic bacteria. Results The minimum inhibitory concentration (MIC) values of curcumin (CCM), meloxicam (MXM), and diclofenac (DC), alone or in combination, were determined using the microdilution broth method. The CCM/MXM combination exhibited synergistic activity against a methicillin-sensitive Staphylococcus aureus (MSSA) strain which is resistant to chloramphenicol and clindamycin. It reduced MICs up to 32-fold and achieved a fractional inhibitory concentration index (FICI) of 0.28 (FICI < 0.5 indicates synergy). Synergy was also observed against a levofloxacin-resistant Enterococcus faecium (FICI = 0.5). Growth kinetics experiments confirmed these findings, with significant reductions in MSSA and E. faecium growth rates ( P < 0.001 and P < 0.01, respectively). Additionally, the biofilm inhibition activity was evaluated. Conclusion These findings suggest that curcumin combined with meloxicam could offer a good antibacterial combination specifically for Gram-positive bacteria. This is a promising approach for topical antibacterial preparations, where high local concentrations can be achieved to combat clinical pathogenic bacteria. Further research on these combinations may support their potential as adjunct therapies for managing bacterial infections or cases of topical infection with concurrent inflammatory disorders.