Bacteria are normally present on the surface of the skin. The bacteria are harmless because the surface of the skin acts as a protective barrier. When this barrier is broken, bacteria can enter the skin beneath the surface and start to grow. Cellulitis is caused by a bacterial infection of the skin.

Common causes of skin breakdown include:

• Lacerations
• Abrasions
• Burns
• Puncture wounds
• Friction blister
• Insect bite or sting
• Animal bites
• Peripheral vascular disease
• Venous insufficiency
• Diabetic skin ulcers