Bacterial infection of the skin, also called cellulitis, occurs when a break in the skin allows bacteria that normally live on the surface to enter the body, causing inflammation, redness, pain, warmth, fever/chills, fatigue and muscle aches. The break itself may arise from an animal or insect bite or sting, after some surgeries, with the use of certain drugs, from skin wounds due to injury, diabetic or ischemic ulcers, or if the patient has peripheral vascular disease. Left untreated, bacterial infection can lead to tissue death (gangrene), sepsis, generalized infection, shock, meningitis (if cellulitis is on the face) and lymphangitis (inflammation of the lymph vessels). Treatment may require hospitalization, oral antibiotics or analgesics to control pain.
Fungal infections of the skin are caused by microscopic organisms that live on the hair, nails (onychomycosis), mouth (angular cheilitis/oral thrush) and outer skin layers. They are quite common; the fungal infection cutaneous candidiasis, for example, which occurs in warm, moist crevices of the body, is the usual cause of diaper rash and vaginal yeast infections. Fungal infections are most likely to occur in people with diabetes, who are obese, or who take antibiotics or oral contraceptives. They are treatable (sometimes with difficulty) but often recur. Treatments include topical and systemic anti-fungal medications.