Sinonasal Stent Coated with Slow-Release Varnish of Chlorhexidine Has Sustained Protection against Bacterial Biofilm Growth in the Sinonasal Cavity: An In Vitro Study

Abstract

The aim of the study was to develop a sustained-release varnish (SRV) containing chlorhexidine (CHX) for sinonasal stents (SNS) to reduce bacterial growth and biofilm formation in the sinonasal cavity. Segments of SNS were coated with SRV-CHX or SRV-placebo and exposed daily to bacterial cultures of Staphylococcus aureus subsp. aureus ATCC 25923 or Pseudomonas aeruginosa ATCC HER-1018 (PAO1). Anti-bacterial effects were assessed by disc diffusion assay and planktonic-based activity assay. Biofilm formation on the coated stents was visualized by confocal laser scanning microscopy (CLSM) and high-resolution scanning electron microscopy (HR-SEM). The metabolic activity of the biofilms was determined using the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) method. Disc diffusion assay showed that SRV-CHX-coated SNS segments inhibited bacterial growth of S. aureus subsp. aureus ATCC 25923 for 26 days and P. aeruginosa ATCC HER-1018 for 19 days. CHX was released from coated SNS segments in a pH 6 medium up to 30 days, resulting in growth inhibition of S. aureus subsp. aureus ATCC 25923 for 22 days and P. aeruginosa ATCC HER-1018 for 24 days. The MTT assay showed a reduction of biofilm growth on the coated SNS by 69% for S. aureus subsp. aureus ATCC 25923 and 40% for P. aeruginosa ATCC HER-1018 compared to the placebo stent after repeated exposure to planktonic growing bacteria. CLSM and HR-SEM showed a significant reduction of biofilm formation on the SRV-CHX-coated SNS segments. Coating of SNS with SRV-CHX maintains a sustained delivery of CHX, providing an inhibitory effect on the bacterial growth of S. aureus subsp. aureus ATCC 25923 and P. aeruginosa ATCC HER-1018 for approximately 3 weeks.

Sinonasal Stent Coated with Sustained-Release Varnish of Mometasone Furoate Inhibits Pro-Inflammatory Cytokine Release from Macrophages: An In Vitro Study

“…This technique has previously been used with other compounds [ 36 ]. The coating was performed on the closed stent, and the varnish was still firmly adhered to the stent upon its opening, as shown in Cataldo et al [ 37 ], which is required for better positioning of the stent in the nasal cavity. Both the plastic and metallic parts were coated with the varnish.…”

“…In contrast, traditional nasal delivery devices (local drops, creams, and sprays) have a rapid release of the active agent and rapid elimination rate of the agent from the nasal mucosa, which is not time-controlled [ 42 , 44 ]. We previously reported some encouraging results with a similar sustained-release system where chlorhexidine was released at active anti-bacterial levels for up to 25 days [ 37 ].…”

Polyglactin 910 Meshes Coated with Sustained-Release Cannabigerol Varnish Inhibit Staphylococcus aureus Biofilm Formation and Macrophage Cytokine Secretion: An In Vitro Study

“…The process was repeated twice, resulting in 60–70 mg of dry SRV film per mesh piece. The coated meshes were allowed to dry completely at room temperature overnight before use [ 27 ].…”

“…Varnishes are liquid pharmaceutical preparations that form a thin film when applied to a surface after drying [ 26 ]. SRVs enriched with various active compounds have been shown to provide long-term antimicrobial and antibiofilm protection in other medical systems, such as oral care [ 26 ], sinonasal cavity [ 27 ], and catheter-associated urinary tract infections [ 28 ].…”