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Methicillin-Resistant Staphylococcus Aureus (MRSA) Infection

Last updated April 23, 2018

Approved by: Maulik P. Purohit MD MPH

Staphylococcus aureus (or Staph) is a commonly occurring bacterium frequently found on the skin (pimples) and in the respiratory tract. It is usually harmless, unless it enters the body through a cut or a wound through contamination of invasive medical devices, or during surgery.


What are the other Names for this Condition? (Also known as/Synonyms)

  • CA-MRSA (Community-Associated Methicillin-Resistant Staphylococcus Aureus) Infection
  • Community-Acquired Methicillin-Resistant Staphylococcus Aureus (CA-MRSA) Infection
  • HA-MRSA (Hospital-Acquired Methicillin-Resistant Staphylococcus Aureus) Infection

What is Methicillin-Resistant Staphylococcus Aureus (MRSA) Infection? (Definition/Background Information)

  • Staphylococcus aureus (or Staph) is a commonly occurring bacterium frequently found on the skin (pimples) and in the respiratory tract. It is usually harmless, unless it enters the body through a cut or a wound through contamination of invasive medical devices, or during surgery
  • Penicillin was commonly used to treat Staphylococcus aureus infections. Over a period of time, penicillin-resistant Staphylococcus aureus bacteria developed. These infections were then treated with methicillin
  • Methicillin is a type of semi-synthetic antibiotic that was found to be effective in penicillin-resistant Staphylococcus aureus infections
  • A variant of this bacterium has been found to have acquired methicillin resistance. Methicillin is an antibiotic belonging to the class of penicillin. This antibiotic-resistant bacterium can be very dangerous in certain conditions
  • Methicillin-Resistant Staphylococcus Aureus Infection (MRSA Infection) could potentially cause severe damage to one’s health, in light of the fact that MRSA is also found to be resistant to numerous other antibiotics
  • In a community, MRSA is known to commonly cause skin infections and the affected individuals may have rashes or lesions on the skin. These infections are called Community-Acquired Methicillin-Resistant Staphylococcus Aureus (CA-MRSA) Infections
  • In a hospital setting, MRSA could cause severe surgical site and bloodstream infections, as well as pneumonia. These infections are called Hospital-Acquired Methicillin-Resistant Staphylococcus Aureus (HA-MRSA) Infections
  • MRSA Infections are detected by testing infected tissues or secretions for the presence of the bacterium
  • The treatment options for Infection due to MRSA range from incision and drainage of lesions to the use of antibiotics, like vancomycin
  • The prognosis for MRSA Infections is influenced by the general health condition of the individual, severity of the infection, as well as the response to treatment

Who gets Methicillin-Resistant Staphylococcus Aureus (MRSA) Infection? (Age and Sex Distribution)

The following individuals are at risk for Methicillin-Resistant Staphylococcus Aureus Infections:

  • Students involved in contact sport activities, such as wrestling
  • Individuals living in crowded settings
  • Individuals in close skin-to-skin contact with infected persons
  • Childcare workers
  • Hospitalized patients who have had surgery
  • Patients with implantable medical devices
  • Patients undergoing kidney dialysis
  • Elderly adults and immunocompromised individuals

What are the Risk Factors for Methicillin-Resistant Staphylococcus Aureus (MRSA) Infection? (Predisposing Factors)

The following are considered risk factors for Community-Acquired Methicillin-Resistant Staphylococcus Aureus Infections (CA-MRSA Infections):

  • Participation in contact sports
  • Athletes sharing sporting equipment and locker room items with others (such as towels and razors)
  • Frequent use of antibiotics
  • Injection drug use
  • Homosexuality; men having sex with men
  • Chronic skin disease occurrence
  • Human immuno-deficiency virus (HIV) positive patients
  • Living in crowded conditions (such as prisons, military barracks, slums)
  • Having skin-to-skin contact with an infected person

Hospital-Acquired Methicillin-Resistant Staphylococcus Aureus Infections (HA-MRSA Infections) may have the following risk factors:

  • Hospitalization, especially of elderly patients
  • Surgical implantation of medical devices
  • Individuals on dialysis
  • Use of venous catheters and prosthetics

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Methicillin-Resistant Staphylococcus Aureus (MRSA) Infection? (Etiology)

  • The most important cause for Methicillin-Resistant Staphylococcus Aureus Infection occurrence is the unnecessary use of antibiotics. For example, using antibiotics for a cold caused by a virus
  • Not completing the full course of an antibiotic prescription
  • Transmission from an infected person or by a contaminated surface

What are the Signs and Symptoms of Methicillin-Resistant Staphylococcus Aureus (MRSA) Infection?

Methicillin-resistant Staphylococcus aureus often enters the body through a cut or scrape and appears in the form of a skin or soft tissue infection.

The signs and symptoms of MRSA Infection may include:

  • A cut, scrape, or boil that becomes inflamed and does not heal
  • A painful, red, or swollen area on the skin often mistaken for a spider bite
  • Infected patients may have fever, fatigue, and chills upon spread of the infection
  • Dizziness and confusion may ensue when the infection spreads

How is Methicillin-Resistant Staphylococcus Aureus (MRSA) Infection Diagnosed?

The following methods may be used to help diagnose a MRSA Infection:

  • Physical examination and complete evaluation of medical history
  • The usual method of diagnosis for Methicillin-Resistant Staphylococcus Aureus Infection is checking a tissue sample or nasal secretions for MRSA organisms, by growing the bacteria in the sample and identifying them. This process takes between 48-96 hours
  • In January 2008, the Food and Drug Administration (FDA) approved the marketing of a quick blood test for detecting MRSA bacteria. This test takes about two hours. However, there are reports that there is a lack of standardization among various such “quick” tests

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Methicillin-Resistant Staphylococcus Aureus (MRSA) Infection?

Methicillin-resistant Staphylococcus aureus (MRSA) bacterial strains are also resistant to multiple antibiotics. Therefore, there may be a likelihood of a life-threatening spread of infection.

The complications of a MRSA Infection may include:

  • Cellulitis (infection of the skin and soft tissues)
  • Blood poisoning (septicemia) occurs when methicillin-resistant Staphylococcus aureus bacterial strains get into the blood stream
  • The bacterial strains can infect the bones causing acute and chronic osteomyelitis
  • It can lead to infected joints possibly resulting in septic arthritis
  • Urinary tract infections (cystitis)
  • Infection of the lungs (pneumonia)
  • Infection of the lining of the heart causing endocarditis. It can also infect the heart valves
  • Very rarely, an antibiotic called Linezolid, if used for MRSA Infection, could result in a drop of all types of blood cells causing pancytopenia. This causes decreased red cells (anemia), decreased white cells (leukopenia), and decreased platelets (thrombocytopenia)

How is Methicillin-Resistant Staphylococcus Aureus (MRSA) Infection Treated?

Treatment plans for Methicillin-Resistant Staphylococcus Aureus (MRSA) Infection depend on the site and seriousness of the infection.

  • For superficial infections, the physician may make an incision in the boil or abscess to drain it out. An antibiotic may or may not be required
  • Infections that have spread internally require intravenous antibiotic treatment, until the patient starts to feel better. This may be followed up with a course of oral antibiotics

How can Methicillin-Resistant Staphylococcus Aureus (MRSA) Infection be Prevented?

There are several common sense methods for preventing Methicillin-Resistant Staphylococcus Aureus (MRSA) Infection. These include:

  • Keeping finger nails short: This will prevent nails from harboring bacteria underneath
  • Washing hands: When possible, soap and water should be used to scrub hands at least for 15 seconds. It is advisable to avoid touching the faucet with clean hands. A disposable paper towel could be used instead
  • Using a hand sanitizer: When water and/or soap is not available, a hand sanitizer should be used to clean one’s hands
  • Not sharing personal items: Personal hygiene items that come in contact with skin, like razors, combs, nail files, toothbrushes, etc. should not be shared. Sharing unwashed towels, sheets, or clothing, should be avoided
  • Keeping wound(s) covered: Any scrape or cut should be cleaned and kept covered to avoid getting infected, as well as to prevent infection from spreading
  • Showering after a sport activity: Immediately after any sport activity, a shower using soap and water may reduce the chances of infection
  • Washing soiled clothing: Soiled clothing and sheets should be washed in hot water and bleach to avoid infection spread
  • Wearing gloves: In a hospital setting, healthcare workers should wear gloves, especially while attending to patients

What is the Prognosis of Methicillin-Resistant Staphylococcus Aureus (MRSA) Infection? (Outcomes/Resolutions)

  • For individuals in good health, the prognosis is reported to be very good following a Methicillin-Resistant Staphylococcus Aureus Infection
  • The prognosis for the section of people prone to MRSA Infection (such as the elderly, hospitalized, and immunocompromised) is a little grave, as they may be susceptible to severe complications following infection

Additional and Relevant Useful Information for Methicillin-Resistant Staphylococcus Aureus (MRSA) Infection:

The following DoveMed website link is a useful resource for additional information:

https://www.dovemed.com/diseases-conditions/infection-center/

What are some Useful Resources for Additional Information?


References and Information Sources used for the Article:


Helpful Peer-Reviewed Medical Articles:


Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: April 27, 2015
Last updated: April 23, 2018