The antibiofilm effect of a medical device (MD) containing TIAB on microorganisms associated with surgical site infections (SSIS)

BACKGROUND-AIM Surgical Site Infections (SSIs) are the most common nosocomial infections. Surgical sutures are optimal surfaces for bacterial adhesion and biofilm formation. The most commonly isolated microorganisms in SSIs are Staphyloccocus aureus (Sa), coagulase-negative Staphylococcus spp., Enterococcus spp., Escherichia coli (Ec) and other Gram-negative bacilli. The aim of this study was to evaluate the antibiofilm activity of a Medical Device (MD) containing TIAB, which is titanium dioxide linked with monovalent silver ions. METHODS Sa ATCC 29213, Enterococcus faecalis (Ef) ATCC 29212, and Ec ATCC 25922 were the micro-organisms used in the study. The antibacterial effect was evaluated by determining the Minimum Inhibitory Concentration (MIC) using the broth microdilution method and the Alamar Blue (AB) assay. The antibiofilm effect was determined by the evaluation of Minimum Biofilm Inibitory Concentration (MBIC). Biofilm inhibition was confirmed by the Live/Dead Cell Viability Staining and Fluorescence Microscopy Analysis. The Colony Forming Unit (CFU) count was performed. The MD was applied on different surgical sutures exposed to the bacterial species. The antimicrobial effect was evaluated by the Agar Diffusion Test (ADT) method, while, the antibiofilm activity was evaluated by Scanning Electron Microscopy (SEM) and Confocal Laser Scanning Microscopy (CLSM). RESULTS The MIC was determined for Sa and Ef at 2 mg/mL while the MBIC was determined at 1.5 mg/mL for Sa and 1 mg/mL for Ef. The formation of an inhibition zone around the treated sutures on agar plates confirmed the antimicrobial activity of MD. The morphological analysis in SEM underlined the presence of a few adhesive cells on the sutures coated with the MD in respect to the control. The functional analysis in Live/Dead Staining and CLSM showed that in treated samples, the majority of adhesive cells were dead. CONCLUSIONS The MD containing TIAB, showed antimicrobial and antibiofilm activities versus Sa and Ef . The MD showed less efficacy against Ec. Surgical sutures coated with the MD have the potential to reduce SSIs as well as the risk of biofilm formation in post-surgery.