[BN]) or left untreated. One hour posttreatment, explants were washed with phosphate-buffered saline (PBS) plus 2% mucin. One, 6, or 12 h later, bacteria were recovered and enumerated. Alternatively, following baseline sampling, human subjects applied two consecutive applications of SNP or saline to their anterior nares. One, 6, and 12 h after application of the preparation (postprep), nasal swabs were obtained, and S. aureus was enumerated. We observed that treatment of infected PM or human skin explants with SNP resulted in >2.0 log 10 CFU reduction in MRSA, regardless of mupirocin sensitivity, which was significantly different from the values for BN-and Bet-treated explants and untreated controls 1 h, 6 h, and 12 h after being washed with PBS plus mucin. Swabbing the anterior nares of human subjects with SNP significantly reduced resident S. aureus compared to saline 1, 6, and 12 h postprep. Finally, pretreatment of PM explants with SNP, followed by a mucin rinse prior to infection, completely prevented MRSA infection. We conclude that SNP may be an attractive alternative for reducing the bioburden of anterior nares prior to surgery.

Aims: To develop a semi-high-throughput ex vivo mucosal model for determining efficacy and toxicity of antiseptics. Methods and Results: Explants (5 mm) from freshly excised, porcine vaginal mucosa were infected with methicillin-sensitive Staphylococcus aureus (1 9 10 6 CFU) at the epithelial surface for 2 h. Haematoxylin and eosin staining revealed healthy uninfected tissue and only minor disruptions in tissue infected with methicillin susceptible Staph. aureus (MSSA), which remained in outer epithelial cell layers. After 2 h infection, 10 ll of chlorhexidine digluconate (CHG, 3%), povidone-iodine (PI, 7Á5%), octenidine dihydrochloride (OCT, 0Á1%) or polyhexamethylene biguanide (PHMB, 0Á1%) was applied. Antiseptics significantly reduced MSSA (1-4 log 10 CFU/explants) after 0Á25 h to 4 h. CHG, PHMB and OCT exhibited persistence at 24 h. In broth culture, CHG 0Á012% and PI 0Á625% achieved >6 log 10 reductions at 2 h. PI-based formulations were more efficacious than unformulated PI. PI-based formulations exhibited no significant cytotoxicity on explants using an MTT assay. Conclusions: All antiseptics tested in the mucosal MSSA infection model reduced MSSA. CHG and PI were more potent in broth culture. Significance and Impact of the Study: We developed a semi-high-throughput mucosal model that can identify compounds or formulations with promising antimicrobial and limited cytotoxic properties.

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