There is provided a method for reducing microbial load at a site on the skin of a subject. The method comprises applying a dressing over the site on the skin of the subject at which a medical procedure that involves breaching the skin is to be performed. As used in the method, the dressing comprises a self-adhesive silicone gel sheet comprising at least about 95 wt % silicone and up to about 5 wt % of particulates of an antimicrobial dispersed in the silicone. The dressing is applied with the silicone gel sheet contacting the skin of the subject and is left in place to allow the antimicrobial to diffuse onto the site.