What is a staph infection?

Staphylococcal infection, commonly called staph infection, are caused by a genus of bacteria called Staphylococcus. There are more than 30 strains (types) of Staphylococcus bacteria and the most common human pathogen is Staphylococcus aureus. Doctors prescribe antibiotics to treat staphylococcal infection. In severe cases, staph infection can cause serious health complications and death.

What parts of the body are affected by staph infection?

Different types of staph bacteria cause problems in various parts of the body. Staphylococcal infection can affect the:

  • Skin: Most commonly, Staphylococcus aureus bacteria cause skin infection. This can produce boils, blisters, and redness on the skin.
  • Breasts: Breastfeeding women can develop mastitis, which causes inflammation (swelling) and abscesses (collections of pus) in the breast.
  • Digestive system: When ingested (eaten), the staph bacteria cause food poisoning, leading to vomiting and diarrhea.
  • Bones: The bacteria can infect the bones, causing inflammation and pain. This infection is called osteomyelitis.
  • Lungs and heart: If the bacteria get into the lungs, abscesses can form, causing pneumonia and breathing problems. Staph bacteria can also damage the heart valves and lead to heart failure.
  • Bloodstream: When bacteria release toxins into the body, a serious infection called septicemia (blood poisoning) can occur.

How common is staph infection?

There are millions of skin staph infections in the United States every year. Most of these cases are mild and treated with antibiotics. It is common for the Staphylococcus bacteria to live on the skin or in the nose of healthy people. The bacteria only cause problems when they make their way inside the body. However, there are many thousands of serious cases of S. aureus infection in the United States every year.

Who is affected by staph infection?

While anyone can get a staph infection, certain groups of people are at higher risk than others. People who work in hospitals are more likely to have the bacteria on their skin. Staph infections occur most often in people who:

  • Inject drugs
  • Are hospitalized, have recently had surgery, or have catheters or medical devices in their body
  • Manage a chronic condition like diabetes or vascular disease
  • Have a weakened immune system
  • Are breastfeeding
  • Have worn a tampon for an extended time
  • Have congenital heart defects
  • Have had other surgeries on heart valves

What are the symptoms of staph infection on the skin?

Symptoms of a staph infection vary depending on the area of the body where the infection occurs. Staph infection occur most often on the skin. Symptoms of staph infection on the skin include:

  • Abscesses and boils: These painful sores form under the skin, causing redness and pain.
  • Cellulitis: This type of infection causes swollen, red, painful skin and tissue just under the skin.
  • Folliculitis: A small pimple-like blister forms under the hair follicle and causes pain.
  • Impetigo: Fluid-filled blisters or sores form and rupture, leaving a yellow or brown crust.
  • Staphylococcal scalded-skin syndrome (SSSS): This serious infection causes skin to peel off all over the body. It usually affects infants and small children.

What are the symptoms of staph infection in the body?

When a staph infection occurs in areas of the body other than the skin, symptoms include:

  • Food poisoning: Symptoms can be severe and include vomiting and diarrhea.
  • Mastitis: Occurring mostly in breastfeeding women, mastitis leads to inflammation, pain, and abscesses in the breast.
  • Septicemia: Staph bacteria in the bloodstream can cause blood poisoning, also called sepsis. Symptoms include fever and dangerously low blood pressure (hypotension).
  • Toxic shock syndrome: A severe form of septicemia, toxic shock syndrome (TSS) symptoms include fever, muscle aches, and a rash that looks like sunburn.
  • Endocarditis: This infection of the lining of the heart muscle is often caused by staph infection. The heart valves and the heart muscle may also be affected. Symptoms include fever, sweating, weight loss, and fast heart rate.

How do people get staph infection?

Staph infection spread in a variety of ways, including:

  • Skin infection: Staph infection on the skin occur when someone comes into contact with the Staphylococcus bacteria. The bacteria are contagious and usually enter into the skin through a cut.
  • Food poisoning: The staph bacteria are ingested (eaten), usually due to cross-contamination when handling food.
  • Toxic shock syndrome: When a woman wears a tampon for an extended time, blood collects on the tampon and creates the ideal environment for bacteria from the woman’s vagina to grow. The bacteria enter into the body through tiny cuts in the lining of the vagina.
  • Mastitis: In breastfeeding women, bacteria from the baby’s mouth enter the breast through a crack in the nipple. When the breast isn’t emptied often, bacteria get trapped in the breast and cause infection.
  • Endocarditis: The bacteria enter the heart through the bloodstream, sometimes through the mouth. People with poor dental health or who bleed when brushing their teeth might be more at risk for this happening.

Last reviewed by a Cleveland Clinic medical professional on 09/17/2019.


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