Staph Infection (Staphylococcus Infection)


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

Symptoms and Causes

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.

Diagnosis and Tests

How is staph infection diagnosed?

Your doctor’s diagnosis of a staph infection depends on what area of the body is affected.

  • Skin: Usually, doctors diagnose a staph infection on the skin by examining the affected area. Your doctor may choose to take a sample of the skin to test for the bacteria.
  • Food poisoning: Your doctor will ask about the length and severity of your symptoms and may take a stool sample.
  • Mastitis: After considering your symptoms, your doctor may send a sample of your breast milk to a lab to test for the presence of bacteria.
  • Toxic shock syndrome: Your doctor may take a urine or blood sample to check for bacteria. Sometimes, doctors will also order a CT scan to see if the infection is affecting the organs.
  • Endocarditis: Diagnosis is based on symptoms, blood tests, and an echocardiogram.

How do I know if I have staph infection?

If you have symptoms of a staph infection, you should contact your doctor for diagnosis and treatment. See your doctor if you or your child has an area of skin that is blistered, irritated, or red, especially if a fever accompanies these symptoms. Only a doctor can diagnose and treat a staph infection.

Management and Treatment

What are the treatments for staph infection?

Most staph infection on the skin can be treated with a topical antibiotic (applied to the skin). Your doctor may also drain a boil or abscess by making a small incision to let the pus out.

Doctors also prescribe oral antibiotics (taken by mouth) to treat staph infection in the body and on the skin. The antibiotic will vary depending on the type of infection. In severe cases of staph infection, doctors use IV (intravenous) antibiotics to kill the bacteria.

What are the side effects of the treatment for staph infection?

Side effects vary depending on the type of antibiotic used to treat the staph infection. Side effects from topical ointments can include stinging, itching, and redness in the affected area. Common side effects of oral antibiotics include nausea, vomiting, and diarrhea.

What are the complications associated with staph infection?

If left untreated, staph infection can be deadly. Rarely, staph infection are resistant to the antibiotics commonly used to treat them. This infection, called methicillin-resistant Staphylococcus aureus (MRSA), cause severe infection and death.

What can I do to help relieve symptoms of staph infection?

It is important to see your doctor if you think you might have a staph infection. To relieve the symptoms of staph infection on the skin, you should clean the affected area with soap and water. Cold compresses and over-the-counter pain relievers may ease the discomfort of skin infection.

In cases of food poisoning, drink plenty of liquids while you are recovering to reduce your risk of dehydration. Massage and warm compresses can relieve the symptoms of mastitis.


How can I prevent staph infection?

Prevention depends on the type of infection. To reduce your risk of a staph infection, you should follow these tips:

  • Skin: To prevent a staph infection of the skin, you should practice good hygiene, keep cuts clean, and wash your hands and body often. Avoid sharing towels and personal items with others.
  • Food poisoning: You can reduce your risk of food poisoning by handling food safely, ensuring that it is cooked properly, and refrigerating perishable food within 2 hours.
  • Toxic shock syndrome: You should change tampons every 4 to 8 hours and use tampons with the lowest effective absorbency.
  • Mastitis: Breastfeeding women should try to empty the breast completely during every feeding. Whenever possible, let nipples air dry.

Outlook / Prognosis

What is the outlook for people who have staph infection?

Most staph infections of the skin are mild. They can be treated with antibiotics and have no lasting effects.

When staph infections are left untreated, they can lead to organ failure and death. In rare cases, methicillin-resistant Staphylococcus aureus (MRSA) infection can be deadly if the infection isn’t controlled.

Living With

When should I call my doctor about staph infection?

Since staph infection can become serious very quickly, you should contact your doctor right away if you have signs of a staph infection. Only a doctor can diagnose and treat a staph infection.

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


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  • American Academy of Pediatrics. Staphylococcal Infection. ( Accessed 11/18/2021.
  • Centers for Disease Control and Prevention. Methicillin-resistant Staphylococcus aureus (MRSA). ( Accessed 11/18/2021.
  • Lowy FD. Lowy F.D. Lowy, Franklin D.Staphylococcal Infection. In: Jameson J, Fauci AS, Kasper DL, Hauser SL, Longo DL, Loscalzo J. Jameson J, Fauci A.S., Kasper D.L., Hauser S.L., Longo D.L., Loscalzo J Eds. J. Larry Jameson, et al.eds. Harrison's Principles of Internal Medicine, 20e New York, NY: McGraw-Hill.
  • American Heart Association. Heart Valves and Infective Endocarditis. ( Accessed 11/18/2021.

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