Zuck, M., Hybiske, K., Jelke, A., Debabov, D., and Anderson, M. NovaBay Pharmaceuticals, Inc., Emeryville, CA

Background: P. aeruginosa and S. aureus are opportunistic human pathogens implicated in many clinical diseases of the eye and skin, including keratitis and impetigo, respectively. Infection can involve destruction of underlying tissue by toxins to exacerbate tissue damage, leading to erosive disease. Developing infected tissue models provide a platform for assessing antimicrobial efficacy and toxicity in that the tissues mimic the in vivo environment; yet maintain the controlled advantages of an in vitro system. N,N-dichloro-2,2-dimethyltaurine (NVC-422) has broad spectrum activity against bacterial pathogens. This study aimed to develop practical in vitro models of primary human cells in tissues superficially infected with bacteria to examine the antimicrobial efficacy of NVC-422. Methods:  Two tissue models were developed: 1) human dermal (EpiDermTM), and 2) ocular (EpiOcularTM) epithelial cells (MatTek Corp). Tissues were cultured on 10 mm transwell inserts and infected with 106 CFU of S. aureus, or P. aeruginosa for 1 h at 37oC. Infected tissues were treated apically with test compounds, rinsed and excised by punch biopsy. Microbial kill was determined by CFU analysis. Toxicity was tested by MTT assay. Infection levels and susceptibility of pathogens to test compounds was confirmed by cryosectioning and immunofluorescence microscopy. Results: Both tissues yielded quantifiable and reproducible superficial infections: 1.5×106 cfu/cm2 P. aeruginosa (EpiOcular), and 1.6×106 cfu/cm2 S. aureus (EpiDermTM)1h topical treatment of 1.5% NVC-422/AA1 and 3h treatment of 0.5% NVC-422/acetate resulted in a 3.2 log and 4 log reduction of S. aureus and P. aeruginosa, respectively. Conclusions:  These results demonstrated the utility and reproducibility of MatTek tissues for modeling superficial infections of human tissue in vitro, and for testing efficacy and toxicity of topical antimicrobials. NVC-422 showed significant bacterial efficacy in both models and support the continued development of NVC-422 as a topical antimicrobial.


Bacterial drugs, CFU analysis, EPI-200-PRF-AFAB, EpiDerm™, EpiOcular™, Impetigo infected tissue models, Infection, Infection model, Keratitia, OCL-200- PRF-AFAB, Opportunistic pathogens, Superficial infections, Topical antimicrobials

Materials Tested

N,N-dichloro-2,2-dimethyltaurine, P. aeruginosa, S. aureus

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