Human skin is teeming with bacteria. Most of these microbes are harmless, but when they manage to make it past a human's tough skin barrier, they can cause itchy and inflamed rashes. Most skin infections are caused by staphylococcus or streptococcus bacteria and are cured with time and a dose of antibiotics. Serious infections can be prevented by cleaning skin cuts and scrapes when they occur, and by frequent hand washing.
Common in young children, this rash is mostly caused by staph bacteria, with a smaller percentage of infections caused by strep bacteria. People with impetigo generally develop red rashes around the nose and mouth with blisters that eventually burst and dry, leaving a yellowish-brown crust. Impetigo is rarely serious, but it is contagious. The rash can be treated with antibiotic ointments for the skin, or with oral antibiotics. The blisters are superficial and do not leave scars.
Strep or staph bacteria can cause deeper infections of the skin, known as cellulitis. Skin will appear swollen, red, and hot and the rash can spread rapidly. People with cellulitis may also have a fever. Unlike impetigo, cellulitis is not contagious because the deeper layers of skin are affected. People with cellulitis should see a doctor for oral or intravenous antibiotics, or they risk a dangerous bacterial infection throughout the body.
Infections of Hair Follicles
When staph bacteria get into a hair follicle, they can cause an itchy rash called folliculitis. Deeper infections around the hair follicles are called furuncles, or boils, and can be painful and hot. A collection of boils in the same area is called a carbuncle. A boil can clear up on its own if the area is kept clean and dry, but carbuncles are more likely to need a doctor’s care to drain away the infected fluid.
Rare but Dangerous Infections
Many bacterial skin rashes clear up on their own, but a few rare varieties always require a doctor’s care. They include diseases like Methicillin-resistant staphylococcus aureus, also known as MRSA. As the name suggests, staph bacteria cause this skin rash, but these particular bacteria are resistant to common antibiotics. Another serious illness is Lyme disease, which is caused by borrelia bacteria passed to humans by ticks. Early signs of the disease include a characteristic bull's-eye skin rash, and if untreated can lead to permanent neurological damage.