Nappy rash: a common form of contact dermatitis

Bacteria: Proteus mirabilis (gut dwelling bacteria) the Staphylococcus aureus

Enzymes: Urease, lipases, proteases,:  Fungi: Candida albicans

The process starts with skin becoming over-hydrated and exposed to friction within the nappy area which starts to damage skin barrier function

1. Faecal bacteria (Proteus mirabilis) grow rapidly on skin in the warm wet environment.

2. P. mirabilis express urease which converts urea in sweat and urine to ammonia

3. Ammonia directly damages the skin causing in effect a chemical burn

4. Ammonia is alkaline so skin pH is raised to > 8

5. High pH causes skin degrading enzymes to be more efficient and morphological change in Candida albicans, found on skin from a harmless spherical form to an invasive hyphal form

6. Severe nappy rash with skin injury results