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

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 × 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 μl 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 0·25 h to 4 h. CHG, PHMB and OCT exhibited persistence at 24 h. In broth culture, CHG 0·012% and PI 0·625% achieved >6 log10 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.

In search of missing links in otology. I. Development of a collagen-based biomaterial

Experiments leading to the development and use of a biomaterial based on reconstituted collagen for use in tympanoplasty are presented. A stable, even membrane with optimal strength and an organized matrix of collagen protein strands has been obtained. Biocompatibility was documented by subcutaneous implantation, cytotoxicity with agar overlay, cell contact, and cell-growth inhibition studies. Experimental grafting in chinchillas with perforated tympanic membranes demonstrated that the collagen membrane performed well in all cases. Histopathological studies in chinchillas showed that the collagen membrane compared favorably with fascia grafts. Of significance is that: 1. The membrane has a matrix of microperforations that enhance tissue ingrowth, allow stable anchoring, and permit aeration of the middle ear cavity. 2. The membranes obtained are not exposed to aldehyde cross-linking; therefore, tissue reaction due to aldehydes is avoided.