An Overview of Staph Infections

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Proper Hand Washing Can Prevent Infections. Image: © Joe Raedle/Getty Images

A "staph" infection is caused by the bacteria Staphylococcus aureus, which normally lives on the skin and in some people, their nose. While this bug usually causes no harm, it may cause an infection if it enters the body.

Skin infections, such as abscesses, or cellulitis, are the most common infections caused by staph, but staph can also enter the bloodstream or other organs (e.g., heart or lung) and cause an infection.

Diagnosis of a staph infection requires a careful medical history, physical examination, and often one or more tests, such as a bacterial culture, blood culture, or imaging test.

Antibiotic therapy is the mainstay treatment of most staph infections—although other therapies like drainage and surgery may also be warranted.

Cause and Risk Factors

A staph infection occurs when the bacteria enters the body, most commonly through a break in the skin. While anyone can develop a staph infection, there are factors that increase a person's risk. 

Some of these risk factors include:

  • Being very young or very old
  • Using injected drugs, such as opioids
  • Being hospitalized or living in a long-term care facility, like a nursing home
  • Having diabetes mellitus or HIV
  • Being on dialysis
  • Requiring long-term intravascular access (e.g., having a chemotherapy port)

Since staph bacteria can spread from one person to another, being in close contact with someone with a staph infection increases your chances for contracting the bacteria.

Staph bacteria may also be present on objects—so sharing athletic equipment or personal items, like razors or towels, may increase your risk. 

Symptoms

The symptoms of a staph infection depend on the type of infection it is causing. Staph is most commonly associated with skin infections, such as abscesses, folliculitis, furuncle, carbuncle, impetigo, and cellulitis, to name a few.

Symptoms such as swelling, warmth, redness, and pain or soreness within or surrounding the infected area are common. Sometimes, a fever is present and the infected skin may drain pus.

If the staph bacteria enter the bloodstream, sepsis may develop, which is very serious and potentially life-threatening.

Other serious staph infections (of which the symptoms are unique to that affected tissue or organ) include:

Staph aureus may also cause toxic shock syndrome, as well as prosthetic joint infections, septic arthritis, and urinary tract infections. 

Diagnosis

Diagnosis of a staph infection requires a comprehensive approach, including a medical history, physical exam, and often tests, like a bacterial culture or various blood tests.

History and Physical Examination

The history and physical examination will be tailored to a person's unique symptoms. For example, for a potential skin infection, your doctor will inspect the affected skin for warmth, redness, tenderness, and drainage. He will also inquire about symptoms that may indicate a more serious infection (e.g., fever or body aches), as well as potential exposures to and risk factors for staph.

Lastly, a key aspect of the physical examination is an evaluation of your vital signs—blood pressure, heart rate, breathing rate, and temperature—as abnormalities can indicate a serious and/or systemic (whole-body) infection.

Culture and Other Tests

A bacterial culture is used to definitively diagnose a skin infection caused by the staph bacteria. Other tests used to access the severity of the infection that may be ordered include blood tests like a complete blood count (CBC), a comprehensive metabolic panel (CMP), and a C-reactive protein level.

Imaging tests to evaluate certain organs (e.g., an echocardiogram for endocarditis or a chest X-ray for pneumonia) may also be ordered.

Treatment

The treatment of a staph infection depends on the type, severity, and location of the infection .

Skin Infections

For some staph skin infections, like an abscess, incision and drainage (where the pus is removed) by a healthcare professional is all that is needed.

If the skin infection is more significant—for example, if an abscess is associated with systemic signs like a fever, extensive cellulitis, or does not improve with drainage of the pus—antibiotic therapy is warranted.

Abscesses located on the face, hands, or genitalia also warrant antibiotic therapy, as do abscesses that occur in individuals with weakened immune systems .

Antibiotics can be given topically (on the skin), orally (by mouth) or intravenously (through the vein), depending on the type and severity of the skin infection.

For example, a topical antibiotic—like Bactroban (mupirocin)—is often sufficient for mild cases of impetigo and folliculitis. For severe skin infections, such as suspected necrotizing fasciitis, hospitalization for intravenous antibiotic administration and other therapies (e.g. surgical debridement or intravenous fluids) may be warranted.

Other Infections

Treatment of non-skin staph infections nearly always involves antibiotic therapy. Sometimes other therapies are utilized too.

For example, an infected joint (septic arthritis) usually involves drainage of the joint space in addition to antibiotic therapy. For an infected prosthetic joint, surgery is required along with antibiotics. Surgical decompression, along with antibiotics, is used to treat staph epidural abscesses .

What Antibiotic Will Your Doctor Prescribe?

The type of antibiotic chosen by your doctor is based not only on the severity of the infection but also on the suspected strain of bacteria causing the infection.

For instance, infections caused by the strain of Staphylococcus aureus that is methicillin-resistant (called MRSA) will not respond to common antibiotics, like amoxicillin and penicillin. Instead, alternative antibiotics such as Bactrim (trimethoprim-sulfamethoxazole) or Zyvox (linezolid) will be used.

Prevention

Good hand and personal hygiene lie at the crux of preventing staph infections. This means washing your hands with soap and water, avoiding sharing personal items with others, and covering any wounds with a bandage until they are healed.

For patients in the hospital with MRSA infections, isolation precautions—such as wearing disposable gowns and gloves—help prevent the spread of infection to the staff and other patients. Disposable equipment such as disposable stethoscopes are also commonly used.

A Words From Verywell

The bottom line here is that while usually a harmless germ, staphylococcus aureus can lead to serious infections. To be proactive, wash your hands thoroughly and frequently and seek medical attention right away for any signs of infection, such as skin redness or warmth, drainage, fever, chills, body aches, or other unusual symptoms.

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Article Sources

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  2. Centers for Disease Control and Prevention. (2011). Staphylococcus aureus in Healthcare Settings.

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  4. Centers for Disease Control and Prevention. (2019). Deadly Staph Infections Still Threaten the U.S.