Coating Doyle Nasal Silicone Splints with a Sustained Release Varnish Containing Antibiotics Provides Long-Term Protection from Staphylococcus aureus: An In Vitro Study

Background/Objectives: Doyle nasal silicone splints are commonly used in nasal surgeries to maintain the shape of the nasal passage and prevent scar tissue formation. However, these implants are prone to bacterial colonization, particularly by Staphylococcus aureus, which is associated with severely recurrent and recalcitrant cases of infected sinonasal cavities. The aim of this study was to develop a sustained-release varnish (SRV) with antibacterial properties that can be applied to Doyle splints to provide an antibacterial environment for an extended period. Methods: Doyle nasal splints (1 cm × 1 cm segments) were coated with SRV containing one of the three antibiotics: augmentin, ciprofloxacin, or chloramphenicol. A placebo varnish without antibiotics served as a control. The coated splints were exposed daily to a fresh culture of S. aureus, and antibacterial activity was assessed by monitoring bacterial growth. Antibiofilm activity was determined using an MTT metabolic assay. Antibacterial activity was further studied by the kinetic disk diffusion assay, where the stents were transferred daily to new, freshly coated S. aureus plates. Biofilm formation on the coated splints was visualized by high-resolution scanning electron microscopy (HR-SEM). Results: Doyle segments coated with augmentin, ciprofloxacin, or chloramphenicol effectively inhibited S. aureus planktonic growth for 9 ± 1, 18 ± 1, and 21 ± 1 days, respectively. Biofilm formation was prevented for 10 ± 1, 18 ± 1, and 21 ± 1 days, and bacterial clearance occurred for 14 ± 1, 52 ± 1, and >65 days, respectively. HR-SEM images showed the prevention of biofilm formation on the coated segments. Conclusions: Our findings demonstrate that coating Doyle nasal silicon splints with SRV containing augmentin, ciprofloxacin, or chloramphenicol provides long-term antibacterial and antibiofilm activity, with SRV–chloramphenicol being superior. Further studies are needed to confirm the in vivo efficacy of this approach.