Ex vivo porcine vaginal mucosal model of infection for determining effectiveness and toxicity of antiseptics

Abstract

To develop a semi-high-throughput ex vivo mucosal model for determining efficacy and toxicity of antiseptics. Explants (5mm) from freshly excised, porcine vaginal mucosa were infected with methicillin-sensitive Staphylococcus aureus (1×10(6) CFU) at the epithelial surface for 2h. 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 2h infection, 10μl of chlorhexidine digluconate (CHG, 3%), povidone-iodine (PI, 7·5%), octenidine dihydrochloride (OCT, 0·1%) or polyhexamethylene biguanide (PHMB, 0·1%) was applied. Antiseptics significantly reduced MSSA (1-4 log10 CFU/explants) after 0·25h to 4h. CHG, PHMB and OCT exhibited persistence at 24h. In broth culture, CHG 0·012% and PI 0·625% achieved >6 log10 reductions at 2h. PI-based formulations were more efficacious than unformulated PI. PI-based formulations exhibited no significant cytotoxicity on explants using an MTT assay. All antiseptics tested in the mucosal MSSA infection model reduced MSSA. CHG and PI were more potent in broth culture. We developed a semi-high-throughput mucosal model that can identify compounds or formulations with promising antimicrobial and limited cytotoxic properties.