General Information

Staphylococcus aureus is Gram-positive cocci that are the common cause of skin infections in the community. Methicillin-resistant Staphylococcus aureus (MRSA) is a type of Staphylococcus aureus bacteria that is resistant to certain antibiotics called beta-lactams. These antibiotics include methicillin and other more common antibiotics such as oxacillin, penicillin, and amoxicillin. Severe or potentially life-threatening infections occur most frequently among patients in healthcare settings. While 25% to 30% of people are colonized* with staph, less than 2% are colonized with it.

*When a person carries the organism/bacteria but shows no clinical signs or symptoms of infection. For S. aureus, the most common body site colonized is the nose.


Recognizing the signs and receiving treatment for the skin infections in the early stages reduces the chances of the infection becoming severe.

Severe Infections: In healthcare settings it usually causes more severe and potentially life-threatening infections, such as bloodstream infections, surgical site infections, or pneumonia. The signs and symptoms will vary by the type and stage of the infection.

Skin Infections: In the community, most infections are skin infections that may appear as pustules or boils which often are red, swollen, painful, or have pus or another drainage.  At first, they often look like spider bites or bumps that are red, swollen, and painful. These skin infections commonly occur at sites of visible skin trauma, such as cuts and abrasions, and areas of the body covered by hair (e.g., back of neck, groin, buttock, armpit, beard area of men).

Preventing the Spread of MRSA in Healthcare Settings

Standard Precautions:

The main principal in standard precautions is to treat all patients as if they are colonized or infected. Healthcare personnel should use some or all of the methods/equipment listed below to protect themselves, their colleagues and other patients at the facility. These include; hand hygiene, use of personal protective equipment (PPE) including gloves, mouth, nose, and eye protection and gowns, appropriate handling of patient care equipment and medical devices and instruments, and cautious handling of soiled linens.

Contact Precautions: Contact precautions are recommended when the facility deems the bacterial infection to be of special clinical and epidemiologic significance. The components of contact precautions may be adapted for use in non-hospital healthcare facilities, especially if the patient has draining wounds or difficulty controlling body fluids.

  1. Placement: Single room or cohort patients with the same infection in the same room or patient-care area.
  2. Gloving: Wear gloves whenever touching the patient’s skin or surfaces and articles in close proximity to the patient (e.g., medical equipment, bed rails). Don gloves upon entry into the room or cubicle.
  3. Gowning: Don gown upon entry into the room or cubicle. Remove the gown and observe hand hygiene before leaving the patient-care environment.
  4. Transport: Limit transport and movement of patients outside of the room to medically-necessary purposes.
  5. Patient-care equipment and instruments/devices: Use disposable noncritical patient-care equipment (e.g., blood pressure cuffs) or implementation of patient-dedicated use of such equipment. If common use of equipment for multiple patients is unavoidable, clean and disinfect such equipment before use on another patient.
  6. Environmental measures: Ensure that rooms of patients on “Contact Precautions” are prioritized for frequent cleaning and disinfection (e.g., at least daily) with a focus on frequently touched surfaces (e.g., bed rails, over bed table, bedside commode, lavatory surfaces in patient bathrooms, doorknobs) and equipment in the immediate vicinity of the patient.

People at Risk of Acquiring MRSA Infections

Historically, infections occurred in hospitalized patients (HA-MRSA), but now these infections are also common in the community (CA-MRSA). The biggest risk factor for infection is open or broken skin; however, infections can occur even on areas of the skin where there is no obvious wound or break in the skin.

Patients in Healthcare Settings

Patients in healthcare facilities have weakened immune systems and undergo procedures (such as surgery) or have catheters inserted into the skin that make it easier for it to gain entry into the body. It is, for this reason, that healthcare personnel must follow infection control procedures (such as hand hygiene and proper catheter care) to prevent the spread of infections. When patients are infected in healthcare facilities, the infections tend to be severe. Common infections include surgical wound infections, urinary tract infections and bloodstream infections, and pneumonia.

Visitors of Infected Patients

When visiting infected patients, individuals should follow the facility’s visitor policies. Casual contact, such as kissing, hugging, and touching, is usually acceptable. Visitors should avoid touching catheters or wound sites and should wash their hands before leaving an infected person’s room.

Skin Infections in the Community

It in the community is widespread and, therefore, anyone is at risk. Most people who get infected in the community get infections of the skin. Factors that have been associated with the spread of skin infections include close skin-to-skin contact, openings in the skin such as cuts or abrasions, contaminated items and surfaces, crowded living conditions, and poor hygiene. People may be more at risk in locations where these factors are common, including athletic facilities, dormitories, military barracks, correctional facilities, and daycare centers.

Diagnosis and Testing of MRSA Infections

It should be included in the differential diagnosis of skin and soft tissue infections (SSTIs) compatible with S. aureus infections, especially those that are purulent (fluctuant or palpable fluid-filled cavity, yellow or white center, central point or “head,” draining pus, or possible to aspirate pus with needle or syringe). A patient presenting a complaint of a “spider bite” should raise suspicion of a S.aureus infection.  Recent data suggest that infection in the community is increasing. The spectrum of disease caused by MRSA appears to be similar to that of Staphylococcus aureus in the community. SSTIs, specifically furuncles (abscessed hair follicles or “boils”), carbuncles (coalesced masses of furuncles), and abscesses, are the most frequently reported clinical manifestations.

Diagnoses: In general, a culture should be obtained from the infection site and sent to the microbiology laboratory. If S. aureus is isolated, the organism should be tested to determine which antibiotics will be effective for treating the infection.

Skin Infection Culturing: A culture of a skin lesion is especially useful in recurrent or persistent cases of skin infection, in cases of antibiotic failure, and in cases that present with advanced or aggressive infections.

Distinguishing CA-MRSA from HA-MRSA

Based on Patient History, persons with the infections that meet all of the following criteria likely have CA-MRSA infections:

  • Diagnosis was made in the outpatient setting or by a culture positive within 48 hours after admission to the hospital.
  • No medical history of infection or colonization.
  • No medical history in the past year of: hospitalization, admission to a nursing home, skilled nursing facility, or hospice, dialysis, or surgery.
  • No permanent indwelling catheters or medical devices that pass through the skin into the body.

Biological Differences of CA-MRSA and HA-MRSA

Recently recognized outbreaks in community settings have been associated with strains that have some unique microbiological and genetic properties compared with the traditional hospital-based strains, suggesting some biologic properties (e.g., virulence factors) may allow the community strains to spread more easily or cause more skin disease. Additional studies are underway to characterize and compare the biologic properties of HA-MRSA and CA-MRSA strains. There are at least three different S. aureus strains in the United States that can cause CA-MRSA infections.

Reporting MRSA to Public Health Authorities

It is reportable in several states. The decision to make a particular disease reportable to public health authorities is made by each state, based on the needs of that individual state.

How to prevent the spread of MRSA?

Good general hygiene including proper cleaning and covering of wounds, hand hygiene, no sharing of personal items, and maintaining a clean environment will all help reduce the risk of transmission. 

Cleaning and Disinfection:

It is known to survive on environmental surfaces for several months so diligent and frequent cleaning and disinfection of environmental surfaces as part of a comprehensive “Environmental Hygiene Plan” should be a key prevention strategy at healthcare, correctional, and athletic facilities. In addition, schools, universities, and other institutions that house large numbers of people should institute similar prevention plans.

It is a Gram-positive bacteria which is susceptible to many Diversey disinfectants.

See table of recommended disinfectants in the PDF link below.

Related Resources

MRSA 09_2019.pdf