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Background: Chronic rhinosinusitis patients (CRS) suffer from chronic inflammation of the sinus mucosa associated with chronic relapsing infections. Mucosal biofilms, associated with Staphylococcus aureus, have been implicated as a cause. We compared the effect of exoproteins secreted from clinical isolates of S aureus from CRS patients in planktonic and biofilm form on the nasal epithelial barrier., Methods: Clinical S aureus isolates from 39 CRS patients were grown in planktonic and biofilm forms and their exoproteins concentrated. These were applied to primary human nasal epithelial cells grown at the air-liquid interface. Transepithelial electrical resistance, permeability of flourescein isothiocyanate-dextrans, and cytotoxicity were measured. Structure and expression of tight junctions zona occludens-1, and claudin-1 proteins were assessed by electron microscopy and immunofluorescence. The Wilcoxon signed rank test was used for statistical analyses., Results: S aureus biofilm exoproteins showed dose- and time-dependent reduction of transepithelial electrical resistance, increased cell toxicity, and increased permeability (p < 0.001) compared with equal concentrations of planktonic cultures. Discontinuity in zona occludens-1 and claudin-1 immunofluorescence was confirmed as disrupted tight junctions on electron microscopy., Conclusion: S aureus biofilm exoproteins disrupt the mucosal barrier structure in a time- and dose-dependent manner and are toxic. Damage to the mucosal barrier by S aureus biofilm exoproteins may play a major role in CRS etiopathogenesis., (© 2020 ARS-AAOA, LLC.)

Background: Chronic rhinosinusitis (CRS) is a common disease, often refractory to conventional antimicrobial treatment. In this study we investigate the antimicrobial and anti-inflammatory effects of adding kappa-carrageenan to a commercially available sinus rinse., Methods: Kappa-carrageenan was added to Flo CRS and Flo Sinus Care sinus rinses and applied directly to air-liquid interface cultured primary human nasal epithelial cells (HNECs) from 10 CRS patients. Inflammatory markers were measured using enzyme-linked immunosorbent assay. Kappa-carrageenan-supplemented sinus rinses were applied to human bronchial epithelial cells (HBEs) in the presence of different Staphylococcus aureus strains to observe the effect on intracellular infection rates., Results: Flo Sinus Care with kappa-carrageenan rinse solutions resulted in a marked reduction of interleukin-6 (IL-6) production by HNECs from CRS patients (p = 0.007). Both Flo CRS and Flo Sinus Care rinses significantly reduced the S aureus intracellular infection of HBEs (p < 0.0001). The addition of kappa-carrageenan to both Flo CRS and Flo Sinus Care rinses further reduced the intracellular infection rate by an average of 2%., Conclusions: The commonly used sinus irrigation product Flo Sinus Care with added kappa-carrageenan reduces IL-6 production by HNECs in vitro. Flo CRS and Flo Sinus Care rinses significantly reduced S aureus intracellular infection rates of HBE cells. Our findings may have clinical relevance for CRS patient management., (© 2019 ARS-AAOA, LLC.)

Background: Topical budesonide (Pulmicort; AstraZeneca AB, Sodertalje, Sweden) is commonly used in the management of chronic rhinosinusitis (CRS). Although its use is due to its perceived anti-inflammatory effect, studies have suggested that it may also have antibacterial properties. To make the hydrophobic steroid molecule suitable for topical administration, pharmaceutical excipients are used in commercial steroid formulations. Herein we investigated the antibacterial action of commercial budesonide and its excipients., Methods: Planktonic and biofilm forms of Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (MRSA) were treated with Pulmicort or its excipients at clinically relevant concentrations. Bacterial growth was determined by optical density, resazurin assays, colony-forming unit counts, and Giemsa staining. Minimum inhibitory concentration (MIC) studies assessed excipients' potentiation of antibiotics. Experiments were conducted in triplicate and results analyzed using one-way analysis of variance., Results: There was significant reduction in planktonic and biofilm growth of S aureus and MRSA on exposure to budesonide (p < 0.0001) and its excipients (p < 0.0001). Excipient ethylene diamine-tetraactic acid (EDTA) demonstrated an antibacterial property even at the low concentrations used in topical preparations (p < 0.0001). With amoxicillin, excipients exhibited a potential additive/synergistic effect on MIC, whereas erythromycin and aminoglycosides showed an antagonistic action., Conclusion: The commercial product Pulmicort has a direct antibacterial effect on the planktonic and biofilm forms of S aureus and MRSA. This effect is at least in part mediated through the excipient EDTA in the product. Excipients also influenced the antimicrobial activity of antibiotics depending on the bacterial strain and antibiotic tested., (© 2019 ARS-AAOA, LLC.)

Background: Staphylococcus aureus biofilms are a nidus for exacerbation of infectious conditions including chronic rhinosinusitis (CRS). Resistance of biofilms to current therapeutics stresses the need for the development of novel anti-biofilm strategies. The chimeric muralytic enzyme P128 was specifically engineered to target Staphylococcal sp. by combining the cell wall binding domain of lysostaphin and the peptidoglycan-degrading murein hydrolase derived from phage K. This study assessed the anti-biofilm activity of P128 against sinus-derived S. aureus., Methods: Biofilms from S. aureus ATCC 25923 and 3 sinus-derived methicillin-sensitive and methicillin-resistant CRS clinical isolates were grown for 48 hours and treated with various concentrations of P128 (0 to 100 μg/mL) for 2 and 24 hours, using the minimum biofilm eradication concentration (MBEC) assay and Alamar Blue (AB) assay. Biofilm present on the MBEC pegs was stained with LIVE/DEAD BacLight stain, imaged using confocal scanning laser microscopy and biomass determined by COMSTAT2 computation. In the AB assay, biofilm was measured by assessing the cell viability. Results were assessed using a Kruskal-Wallis test, with a Wilcoxon post hoc test and Bonferroni correction., Results: Both the MBEC and AB assay indicated that P128 was effective against in vitro S. aureus biofilms with significant reductions in biofilm of up to 95.5% at concentrations ≥12.5 μg/mL for all tested strains., Conclusion: The engineered chimeric endolysin P128 was observed to be an effective anti-biofilm agent against S. aureus. Further study will proceed into the appropriate application of P128 to ensure both an economically and clinically feasible preparation., (© 2015 ARS-AAOA, LLC.)

Background: The presence of Staphylococcus aureus biofilms on sinonasal mucosal surfaces is associated with recalcitrant chronic rhinosinusitis (CRS), but little is known about the innate immune response they trigger. We aimed to study the human pattern recognition receptor (PRR) nucleotide-binding oligomerization domain containing 2 (Nod2) receptor and downstream pathway in response to initial S. aureus biofilm infection., Methods: Using a validated protocol, sinonasal mucosae from 4 non-CRS donors were cultured with and without S. aureus biofilms and planktonic cells. After 24 hours, RNA was extracted and gene expression was analyzed using a human antibacterial response polymerase chain reaction (PCR) array. Immunohistochemistry was performed to confirm the presence and determine the immunolocalization of selected proteins., Results: C-X-C motif (CXC) chemokine ligands 1 and 2, interleukin-6 (IL-6), and genes related to the Nod2 pathway were significantly upregulated in biofilm-treated tissues compared with control samples. Nod2 pathway-specific gene expression was increased in biofilm-treated tissues compared with planktonic S. aureus-treated explants. Enhanced expression of Nod2 and nuclear factor kappa B1 (NF-κB1) was also detected with immunohistochemistry in control and biofilm-treated tissues., Conclusion: S. aureus biofilms exerted a proinflammatory response in the mucosa and activation of the Nod2 pathway, indicating this receptor to be involved in the innate immune response to S. aureus biofilms. Further studies are required to elucidate the role of this pathway in CRS., (© 2013 ARS-AAOA, LLC.)

Background: Staphylococcus aureus (S. aureus) biofilm has been associated with severe and recalcitrant cases of chronic rhinosinusitis (CRS). However, its role in the pathophysiology of this condition is not completely understood. This study aims to develop a sinonasal tissue explant model to analyze the interaction of S. aureus biofilm with the mucosa in vitro., Methods: Sinonasal tissue samples from 5 control patients undergoing pituitary surgery were cultured with and without S. aureus biofilm in vitro. Confocal scanning laser microscopy (CSLM) using the Live/Dead BacLight stain and histology were performed on the tissue explants after 24 hours of biofilm challenge. Measurements of IL-6, at both the messenger RNA (mRNA) level (using quantitative reverse-transcriptase polymerase chain reaction [qRT-PCR]) and the protein level (using enzyme-linked immunosorbent assay [ELISA]), were undertaken to evaluate biofilm-mucosa interaction., Results: Viability of the explants after 24 hours was confirmed by CSLM and histology. Although light microscopy failed to identify S. aureus biofilms, its presence was confirmed in the biofilm-challenged samples by CSLM. IL-6 mRNA transcript levels were 4.9-fold upregulated in biofilm-treated tissue compared to controls (p = 0.0485). A similar trend was observed at the protein level (p = 0.0313)., Conclusion: The sinonasal tissue explant is a viable and functional model capable of analyzing direct biofilm-mucosal interactions and can advance our understanding of the role played by S. aureus biofilm in sinus inflammation. Our model suggests that S. aureus biofilms in the initial phase of growth are not inert bystanders but elicit an immune response in the sinonasal mucosa., (© 2013 ARS-AAOA, LLC.)