METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS (MRSA)

COMMUNITY ACQUIRED vs. HEALTHCARE ASSOCIATED

Recently, there have been a number of reports about methicillin-resistant Staph aureus (MRSA) infections in schools. There are many resources available for individuals with questions about MRSA infections. Below is some general information about MRSA. There is also a fact sheet regarding MRSA on the Pennsylvania Department of Health web site (www.health.state.pa.us).

What is Staphylococcus aureus?

Staphylococcus aureus, often referred to simply as "staph," is commonly carried on the skin or in the nose of healthy people. Approximately 25% to 30% of the population is colonized (when bacteria are present, but not causing an infection) with staph bacteria in the nose or on the skin. Sometimes, staph can cause an infection. Staph is among the most common causes of skin infections in the United States. Most of these skin infections are minor (such as pimples and boils) and can be treated without antibiotics (also known as antimicrobials or antibacterials). However, in some instances staph can cause serious infections (such as surgical wound infections, bloodstream infections, and pneumonia).

What is MRSA (methicillin-resistant Staphylococcus aureus)?

Some staph bacteria are resistant to antibiotics. MRSA is a type of staph that is resistant to the antibiotic methicillin and its close cousins oxacillin, penicillin and amoxicillin. While 25 percent to 30 percent of the population is colonized with staph, only about 1 percent normally carries MRSA.

Who gets staph or MRSA infections?

Staph infections, including MRSA, occur most frequently among persons in hospitals and healthcare facilities (such as nursing homes and dialysis centers) who have weakened immune systems. These healthcare-associated staph infections include surgical wound infections, urinary tract infections, bloodstream infections, and pneumonia and are quite different from the MRSA infections that occur in the community setting

What is community-associated MRSA (CA-MRSA)?

Another form of MRSA can cause illness in persons outside of hospitals and healthcare facilities. This community form of MRSA occurs in persons who have not been recently (within the past year) hospitalized nor had a medical procedure (such as dialysis, surgery, catheters) and is known as CA-MRSA. This type of MRSA usually produces skin infections, such as pimples and boils.

How is MRSA transmitted in the community?

The main mode of spread of all forms of staph, including MRSA, is by the hands and skin-to-skin contact, crowded conditions, and poor hygiene. The sharing of towels, personal hygiene items like razors, athletic equipment, clothes, nonsterilized tattoo instruments, and illicit drug paraphernalia also promote the spread of S.aureus from one individual to another. Habits like body shaving are also thought to promote MRSA infection.

Although MRSA has been isolated from environmental surfaces (e.g., floors, work areas, medical equipment) and pets, these are not considered to be the most important sources for spread and there is no need to do environmental sampling in any affected facility. However, it is important to routinely clean shared items like athletic equipment.

What are the risk factors for CA-MRSA?

Although there have been documented outbreaks of CA-MRSA in numerous settings and associated with a number of activities, it is important to remember that CA-MRSA may occur in otherwise healthy persons with no traditional MRSA associated risk factors. CA-MRSA knows no age boundaries and has been documented in newborns, toddlers, teens, adults, and the elderly. A recent study (2007) concluded that there are no reliable markers to distinguish patients with CA-MRSA infection from patients with other skin infections caused by staph. Populations in which MRSA clusters have been documented:

-- Athletes in contact sports

-- Intravenous drug and methamphetamine users

-- Inmates at correctional facilities

-- Military personnel

Medical history also plays a factor in contraction of MRSA infection:

-- Recent hospitalization

-- Recurrent or recent antibiotic use

-- Recurrent skin disease

-- Recurrent or recent skin damage

Environmental conditions also play a role:

-- Living in crowded or unsanitary conditions

-- Close contact with someone known to be infected or colonized with MRSA

-- High incidence of MRSA in the community

What are the clinical features of CA-MRSA?

CA-MRSA most often presents as skin or soft tissue infection such as a boil or abscess. Pimples, rashes, pus-filled boils, especially when warm, painful, red or swollen, can indicate a staph skin infection. Impetigo is one example of a skin infection that can be caused by staph, including MRSA. Patients frequently recall a “spider bite”. Staph infections also can cause more serious infections, such as blood stream infections or pneumonia, leading to symptoms of shortness of breath, fever, and chills.

What are the criteria for distinguishing community-associated MRSA (CA-MRSA) from healthcare-associated MRSA (HA-MRSA)?

Persons with MRSA infections that meet all of the following criteria are likely to have CA-MRSA infections:

• Diagnosis of MRSA was made in the outpatient setting or by a culture positive for MRSA less than 48 hours after admission to the hospital.
• No medical history of MRSA infection or colonization.
• No medical history in the past year of:
• Hospitalization
• Admission to a nursing home, skilled nursing facility, or hospice
• Dialysis
• Surgery
• No permanent indwelling catheters or medical devices that pass through the skin into the body.

How is a MRSA infection diagnosed?

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.

How is CA-MRSA treated?

Most MRSA infections are treated by simply administering good wound and skin care: incision and draining of boils by a health care provider, keeping the area clean and dry, washing hands after caring for the area, carefully disposing of any bandages, and allowing the body to heal.

In some instances, antibiotics are also used to treat MRSA. However, several studies have shown that MRSA skin infections generally heal just as quickly with proper care whether or not antiobics have been used. If antibiotics are needed, it is important for the patient to use the medication as directed unless the healthcare provider says to stop. If the infection has not improved within a few days after seeing the healthcare provider, the student should contact the provider again.

How do CA-MRSA and HA-MRSA strains differ?

Recently recognized outbreaks of MRSA in community settings have been associated with strains that have some unique microbiologic and genetic properties compared with the traditional hospital-based MRSA strains. In general, CA-MRSA strains are much less resistant to common antibiotics other than methicillin than strains found in the hospital setting.

Are MRSA infections a reportable disease?

Individual cases of MRSA are not reportable in Pennsylvania, like in many other states. Cluster or outbreaks of CA-MRSA should be reported to the Pennsylvania Department of Health under the Communicable and Non-Communicable Disease Regulations. As of today the majority of reported CA-MRSA outbreaks have been the result of skin and soft tissue infections.

To prevent MRSA infections in community settings, consider these guidelines:

• Regular handwashing is the best way to prevent getting and spreading staph/MRSA. Encourage and practice hand hygiene.
• Practice and encourage good skin care. Since staph infections begin when staph enters the body through a break in the skin, keeping skin healthy and intact is an important preventative measure.
• Ensure access to sinks, soaps, and clean towels.
• Ensure the availability of alcohol-based hand sanitizers, if soap and water are not accessible.
• Educate employees (i.e., coaches, athletic trainers, etc.) about the importance of personal hygiene for students.
• Encourage daily showers with soap and water.
• Discourage sharing of personal items such as towels, razors, and toothbrushes.
• Regularly clean sinks, showers, and toilets by saturating with disinfectant.
• Disinfect athletic equipment between users.
• Launder sheets, towels, sports uniforms, and underclothing with hot water and detergent, and dry on the hottest setting.
• Wear gloves when handling dirty laundry.
• Wear gloves when caring for another person’s wounds, and protect clothing from touching wounds or bandages.
• Encourage those infected to always keep draining lesions covered with dressings.
• Dispose of dressings containing pus and blood carefully.
• Disinfect contaminated portable equipment such as stethoscopes, blood-pressure cuffs, equipment handles, tourniquets, pagers, and cell phones.

What information on MRSA is available:

For more information about MRSA, visit:

• Pennsylvania Department of Health www.health.state.pa.us
• Centers for Disease Control and Prevention. CA-MRSA Information for Providers at http://www.cdc.gov/ncidod/dhqp/ar_mrsa_ca.html