I think Anna might be right that you need to kill the yeast in the diaper and then use a really thick barrier cream. (greenbabyguide.com)
In comparison to other creams it has the thickest barrier, stays for a long time and seals the wetness out. (thankyourbaby.com)
Two layers of EPP (Expanded Polyproplyene) foam provide a thick barrier around the child's head and body to absorb the energy from side impact crashes. (bestcarseathub.com)