Diclofenac sodium effectively inhibits the biofilm formation of Staphylococcus epidermidis.

Staphylococcus epidermidis is an opportunistic pathogen commonly implicated in medical device-related infections. Its propensity to form biofilms not only leads to chronic infections but also exacerbates the issue of antibiotic resistance, necessitating high-dose antimicrobial treatments. In this study, we explored the use of diclofenac sodium, a non-steroidal anti-inflammatory drug, as an anti-biofilm agent against S. epidermidis. In this study, crystal violet staining and confocal laser scanning microscope analysis showed that diclofenac sodium, at subinhibitory concentration (0.4 mM), significantly inhibited biofilm formation in both methicillin-susceptible and methicillin-resistant S. epidermidis isolates. MTT assays demonstrated that 0.4 mM diclofenac sodium reduced the metabolic activity of biofilms by 25.21-49.01% compared to untreated controls. Additionally, the treatment of diclofenac sodium resulted in a significant decrease (56.01-65.67%) in initial bacterial adhesion, a crucial early phase of biofilm development. Notably, diclofenac sodium decreased the production of polysaccharide intercellular adhesin (PIA), a key component of the S. epidermidis biofilm matrix, in a dose-dependent manner. Real-time quantitative PCR analysis revealed that diclofenac sodium treatment downregulated biofilm-associated genes icaA, fnbA, and sigB and upregulated negative regulatory genes icaR and luxS, providing potential mechanistic insights. These findings indicate that diclofenac sodium inhibits S. epidermidis biofilm formation by affecting initial bacterial adhesion and the PIA synthesis. This underscores the potential of diclofenac sodium as a supplementary antimicrobial agent in combating staphylococcal biofilm-associated infections.