What Is a Staph Infection?

Petri dish with a culture of Staphylococcus aureus bacteria

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Staphylococcal (staph) infection is caused when bacteria called Staphyloccocus enters the body, usually through a skin cut or wound. Staphyloccocus aureus is the most common type to infect humans, though there are more than 30 others. While staph normally lives in the nose or on the skin of some healthy individuals without consequence, infections can cause abscesses, cellulitis, or other skin concerns, and can less commonly infect the bloodstream or other organs (e.g., heart, lung, or bone).

In the majority of cases, antibiotics can successfully treat staph infections. However, some cases can be resistant and even life-threatening.

What to Know About Staph Infections
Verywell / Gary Ferster

Staph Infection 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 fatal.

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

Staph may also cause:

When to Seek Immediate Medical Attention

While symptoms of a staph infection are highly variable (based on the affected organ), these symptoms warrant emergent medical attention:

  • Severe headache, neck stiffness, and fever
  • Painful rash or rash associated with a fever
  • Rapid heart rate and/or breathing rate
  • Chest pain or trouble breathing
  • Severe or persistent vomiting or diarrhea and/or signs of dehydration
  • Swelling or pain around a device, such as an intravenous line, pacemaker, or replacement joint

Causes

Many different types of staph live on the human body (this is called colonization). For example, Staphylococcos aureus colonizes the noses of about 30% of healthy people and the skin of about 20% of people.

Besides living on people, staph can live on objects, such as doorknobs or athletic equipment. A person can become colonized with staph by simply touching the skin of someone who is colonized or by touching or sharing a contaminated object (e.g., a towel or razor).

That said, colonization is not the same as an infection. Being colonized with staph causes no symptoms. On the other hand, when staph enters the body causing an infection, symptoms do occur. The bacteria most commonly find their way through a break in the skin (e.g., a minor cut from shaving or a wound from trauma).

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
  • Having a chronic skin or lung disease
  • Having an open wound
  • Being on a drug that weakens your immune system (e.g., corticosteroids)
  • 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
  • Having a transplanted organ or an implanted medical device (e.g., artificial heart valve, pacemaker, or joint)
  • Being on dialysis
  • Having long-term intravascular access (e.g., having a chemotherapy port)

Diagnosis

Diagnosis of a staph infection requires 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 your unique symptoms. For example, for a potential skin infection, your doctor will inspect the affected skin for warmth, redness, tenderness, and drainage. They 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.

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 of some kind.

Culture and Other Tests

A bacterial culture is used to definitively diagnose a skin infection caused by staph bacteria. Other tests that may be ordered to assess the severity of the infection 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

Once diagnosed with a staph infection, antibiotic therapy is the mainstay treatment.

Antibiotics can be given topically (on the skin), orally (by mouth) or intravenously (through the vein).

The specific antibiotic chosen depends on two main factors:

  • The severity of the infection
  • Whether the staph bacteria is resistant to any antibiotics

Severity

Mild or moderate staph infections can generally be treated with topical or oral antibiotics.

For example, a topical antibiotic like Bactroban (mupirocin) may be considered to treat mild cases of impetigo and folliculitis. Likewise, an oral antibiotic, such as Keflex (cephalexin), may be used to treat mastitis or nonpurulent cellulitis (cellulitis with no drainage of pus and no associated abscess).

Intravenous antibiotics, such as Vancocin (vancomycin), which are given directly into the bloodstream, are required to treat severe staph infections, like osteomyelitis, pneumonia, and sepsis.

Resistance

While many staph infections can be treated with methicillin or a similar antibiotic, like Keflex (cephalexin), some staph bacteria are resistant to methicillin. These bacteria are called methicillin-resistant Staphylococcus aureus (MRSA).

To determine which antibiotics are effective against the staph, doctors can perform an antibiotic susceptibility test in a lab setting.

Then, based on where the infection was contracted, doctors can choose to treat the MRSA infection with a certain oral or intravenous antibiotic.

Hospital-acquired MRSA infections are usually serious and potentially life-threatening. They require treatment with an intravenous antibiotic like Vancocin (vancomycin) or Cubicin (daptomycin). Once discharged from the hospital, patients often go home with oral antibiotics or intravenous antibiotics administered through a PICC line.

Community-acquired MRSA infections tend to not be as serious or fatal. They can often be treated with oral antibiotics, like Bactrim (trimethoprim-sulfamethoxazole) or Cleocin (clindamycin).

Other Therapies

It's important to keep in mind that the treatment of staph infections may involve additional therapies along with antibiotics.

For example, an abscess usually requires incision and drainage (where the pus is removed). Similarly, an infected joint (septic arthritis) usually involves drainage of the joint space, in addition to antibiotic therapy.

For an infected bone or prosthetic joint, surgical debridement is required along with antibiotics.

Surgical decompression, along with antibiotics, is used to treat staph epidural abscesses.

Prevention

Good hand and personal hygiene are at the crux of preventing staph infections. This means thoroughly 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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  1. King JM, Kulhankova K, Stach CS, Vu BG, Salgado-pabón W. Phenotypes and Virulence among Staphylococcus aureus. USA100, USA200, USA300, USA400, and USA600 Clonal Lineages. mSphere. 2016;1(3). doi:10.1128/CMR.00134-14

  2. Cleveland Clinic. (September 2019). Staph Infection (Staphylococcus Infection)

  3. Tong SY, Davis JS, Eichenberger E, Holland TL, Fowler VG Jr. Staphylococcus aureus infections: epidemiology, pathophysiology, clinical manifestations, and management. Clin Microbiol Rev. 2015 Jul;28(3):603-61. doi:10.1128/CMR.00134-14

  4. Sukumaran V, Senanayake S. Bacterial skin and soft tissue infections. Aust Prescr. 2016;39(5):159-163. doi:10.18773/austprescr.2016.058

  5. Bush L. (Modified June 2019). Merck Manual Consumer Version. Staphylococcus aureus Infections. (Staph Infections)

  6. De oliveira TH, Amorin AT, Rezende IS, et al. Sepsis induced by Staphylococcus aureus: participation of biomarkers in a murine model. Med Sci Monit. 2015;21:345-55. doi:10.12659/MSM.892528

  7. Harris A (Updated January 2019). Patient education: Methicillin-resistant Staphylococcus aureus (MRSA) (Beyond the Basics). Lowy FD, ed. UpToDate. Waltham, MA: UpToDate.

  8. Centers for Disease Control and Prevention. Invasive Methicillin-Resistant Staphylococcus aureus Infections Among Persons Who Inject Drugs. Six Sites, 2005–2016.

  9. Hassanzadeh P, Hassanzadeh Y, Mardaneh J, Rezai E, Motamedifar M. Isolation of Methicillin-Resistant Staphylococcus aureus (MRSA) from HIV Patients Referring to HIV Referral Center, Shiraz, Iran, 2011-2012. Iran J Med Sci. 2015;40(6):526-30.

  10. Chu C, Wong MY, Tseng YH, et al. Vascular access infection by Staphylococcus aureus from removed dialysis accesses. Microbiologyopen. 2019;8(8):e00800. doi:10.1002/mbo3.800

  11. Tong SY, Davis JS, Eichenberger E, Holland TL, Fowler VG Jr. Staphylococcus aureus infections: epidemiology, pathophysiology, clinical manifestations, and management. Clin Microbiol Rev. 2015 Jul;28(3):603-61. doi:10.1128/CMR.00134-14

  12. Romero-gómez MP, Cendejas-bueno E, García rodriguez J, Mingorance J. Impact of rapid diagnosis of Staphylococcus aureus bacteremia from positive blood cultures on patient management. Eur J Clin Microbiol Infect Dis. 2017;36(12):2469-2473. doi:10.1007/s10096-017-3086-5

  13. Missiakas DM, Schneewind O. Growth and laboratory maintenance of Staphylococcus aureus. Curr Protoc Microbiol. 2013;Chapter 9:Unit 9C.1. doi: 10.1002/9780471729259.mc09c01s28

  14. Kobayashi SD, Malachowa N, Deleo FR. Pathogenesis of Staphylococcus aureus abscesses. Am J Pathol. 2015;185(6):1518-27. doi:10.1016/j.ajpath.2014.11.030

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

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