Amy was used to the occasional outbreak of zits, but the bump on her neck was different. It started out fairly small and itchy, but now was big and red and sore. Amy's mom took her to the doctor and they were surprised to hear that the bump was a boil, an infection usually caused by staph bacteria.

What Is a Staph Infection?

Staph (pronounced: staff) is the shortened name for Staphylococcus (pronounced: staf-uh-low-kah-kus), a type of bacteria. These bacteria can live harmlessly on many skin surfaces, especially around the nose, mouth, genitals, and anus. But when the skin is punctured or broken for any reason, staph bacteria can enter the wound and cause an infection.

There are more than 30 species in the staph family of bacteria, and they can cause different kinds of illnesses — for example, one kind of staph can cause urinary tract infections. But most staph infections are caused by the species Staphylococcus aureus (S. aureus).

S. aureus most commonly causes skin infections like folliculitis, boils, impetigo, and cellulitis that are limited to a small area of a person's skin. S. aureus can also release toxins (poisons) that may lead to illnesses like food poisoning or toxic shock syndrome.

How Do People Get Staph Infections?

In teens, most staph infections are minor skin infections. People with skin problems like burns or eczema may be more likely to get staph skin infections.

People can get staph infections from contaminated objects, but staph bacteria often spread through skin-to-skin contact — the bacteria can be spread from one area of the body to another if someone touches the infected area.

Staph infections can spread from person to person among those who live close together in group situations (such as in college dorms). Usually this happens when people with skin infections share things like bed linens, towels, or clothing. Warm, humid environments can contribute to staph infections, so excessive sweating can increase someone's chances of developing an infection.

Serious Staph Infections

Infections caused by S. aureus can occasionally become serious. This happens when the bacteria move from a break in the skin into the bloodstream. This can lead to infections in other parts of the body, such as the lungs, bones, joints, heart, blood, and central nervous system.

Staph infections in other parts of the body are less common than staph skin infections. They are more likely in people whose immune systems have been weakened by another disease — or by certain medications, like chemotherapy for cancer.

Occasionally patients having surgery may get more serious types of staph infections. The good news is that hospital staff take many precautions to avoid infection in someone having surgery. That's why they carefully clean the area being operated on, use sterile equipment, and sometimes give a person antibiotics.

You may also have heard about methicillin-resistant Staphylococcus aureus or MRSA for short. MRSA is a type of staph that has built up a resistance to the antibiotics usually used to treat staph infections. Although MRSA can be harder to treat, in most cases the infection heals with the right treatment.

What Are the Signs of a Staph Skin Infection?

Staph skin infections show up in lots of different ways. Some of the more common conditions often caused by S. aureus skin infections are:

• Folliculitis (pronounced: fuh-lih-kyoo-lie-tus) is an infection of the hair follicles, the tiny pockets under the skin where hair shafts (strands) grow. In folliculitis, tiny white-headed pimples appear at the base of hair shafts, sometimes with a small red area around each pimple. This occurs often where people shave or have irritated skin from rubbing against clothing.
• A furuncle (pronounced: fyoor-un-kul), commonly known as a boil, is a swollen, red, painful lump in the skin, usually due to an infected hair follicle. The lump usually fills with pus, growing larger and more painful until it ruptures and drains. Furuncles often begin as folliculitis and then worsen. They are most frequently found on the face, neck, buttocks, armpits, and inner thighs, where small hairs can often be irritated. A cluster of several furuncles is called a carbuncle (pronounced: kar-bun-kul). A person with a carbuncle may feel ill and feverish.
• Impetigo (pronounced: im-puh-tie-go) is a superficial skin infection that mostly happens in young children, but it can sometimes affect teens and adults. Most impetigo infections affect the face or extremities like the hands and feet. An impetigo skin infection begins as a small blister or pimple, and then develops a honey-colored crust. Impetigo doesn't usually cause pain or fever, although the blisters may itch and can be spread to other parts of the body by scratching.
• Cellulitis (pronounced: sell-yuh-lie-tus) is an infection involving the skin and areas of tissue below the skin surface. It begins as a small area of redness, pain, swelling, and warmth on the skin. As this area begins to spread, a person may feel feverish and ill. Cellulitis can affect any area of the body, but it's most common on the legs.
• A hordeolum (pronounced: hore-dee-oh-lum), commonly known as a sty (or stye), is a staph infection in the eyelid. It develops when glands connected to the base of the eyelash become swollen and irritated. A person with a sty will usually notice a red, warm, uncomfortable, and sometimes painful swelling near the edge of the eyelid.

Many of these staph infections are minor and can be treated at home. If a minor infection gets worse — for example, you start feeling feverish or ill or the area spreads and gets very red or and hot — it's a good idea to see a doctor.

Wound infections generally show up 2 or more days after the injury or surgery. The signs of a wound infection (redness, pain, swelling, and warmth) are similar to those found in cellulitis. A wound infection may be accompanied by fever and a generally ill feeling. Pus or a cloudy fluid can drain from the wound and a yellow crust (like that in impetigo) can develop. If you think you have a wound infection after surgery, or you have a serious wound that seems to be infected, call your doctor.

Can I Prevent a Staph Skin Infection?

Staphylococcus aureus bacteria are everywhere. Many healthy people carry staph bacteria without getting sick.

Cleanliness and good hygiene are the best way to protect yourself against getting staph (and other) infections — including MRSA. You can help prevent staph skin infections by washing your hands frequently and by bathing or showering daily.

Keep areas of skin that have been injured (such as cuts, scrapes, eczema, and rashes caused by allergic reactions or poison ivy) clean and covered. Use any antibiotic ointments or other treatments that your doctor suggests. If someone in your family has a staph infection, don't share towels, sheets, or clothing until the infection has been fully treated.

If you develop a staph infection, you can prevent spreading it to other parts of your body by being careful not to touch the infected skin, keeping it covered whenever possible, and using a towel only once when you clean the area (wash the towel in hot water afterwards or use disposable towels).

What Can I Do to Feel Better?

How long it takes for a staph skin infection to heal depends on the type of infection and whether a person gets treatment for it. A boil, for example, may take 10 to 20 days to heal without treatment, but treatment may speed up this process. Most styes, on the other hand, go away on their own within several days.

To help relieve pain from a skin infection, and to help pus drain out, try soaking the affected area in warm water or applying warm, moist washcloths. Use a clean washcloth each time — wash used cloths in soap and hot water and dry them fully in a clothes dryer. You can also apply a heating pad or a hot water bottle to the skin for about 20 minutes, three or four times a day.

Pain relievers like acetaminophen or ibuprofen can help reduce pain until the infection subsides. For some skin infections, it can also help to wash the area with an antibacterial cleanser and apply an antibiotic ointment. Cover the skin with a clean dressing.

A sty can be treated using warm compresses over the eye (with the eye closed) three or four times a day. Be sure you always use a clean washcloth each time. Occasionally, a sty will require a topical antibiotic. See your doctor if a sty doesn't go away in a few days.

If you get a staph infection on skin areas that you normally shave, avoid shaving, if possible, until the infection clears up. If you do have to shave the area, use a clean disposable razor or clean your electric razor after each use.

Reviewed by: Stephen C. Eppes, MD
Date reviewed: April 2011