Methicillin-Resistant Staphylococcus aureus

(An Overview)

Pathogen

Staphylococcus aureus, gram-positive aerobic bacterium resistant to cloxacillin and other antibiotics.

Symptoms

Carriers may not manifest any symptoms. However, patients can develop a variety of infections with MRSA: surgical site, pneumonia, UTI, bacteremia, skin and decubitus ulcer infections. Symptoms are the same as if the causative organism were methicillin sensitive. However, treatment and eradication of the infection may be more difficult.

Incubation Period

Variable. Commonly 4 to 10 days.

Reservoir

Infected or colonized individuals.

Mode of Transmission

Direct and indirect contact, the most frequent form being contact with the contaminated hands of health care providers and/or their contaminated patient care equipment. MRSA is commonly carried in the anterior nares and groins of colonized individuals. It can also be found in the transient flora of their hands. In infected persons, the bacteria are found in the infected sites. Transmission in the home has not frequently been reported.

Communicability

As long as the organism can be recovered from a body site the risk of transmission remains. Carriage can be transient, but MRSA may be present in undetectable numbers, therefore negative cultures do not necessarily mean the patient is no longer colonized. A person who has carried MRSA may recolonize at any time and should always be examined with gloves to prevent possible transmission to other patients or staff.

Treatment

Vancomycin is the drug of choice for empiric therapy. Some strains of MRSA are sensitive to other antibiotics and these may be used once sensitivities are determined.

Prevention & Control

Strict isolation of patients colonized or infected with MRSA while they are in hospital. In the examining room disinfect anything that has come in contact with the patientÕs skin, drainage or secretions.

Caregivers should wear gloves for all contact and wash hands immediately after glove removal. Avoid touching your face, especially the eyes and nose with gloved or unwashed hands.

Culturing for MRSA

People at increased risk for colonization are those with wounds, catheters, drains and non-intact skin. The presence of these factors in many hospitalized individuals contributes to greater risk of transmission in acute-care facilities than the community setting. Health care workers may become colonized and represent the source of MRSA but this is not common. Transmission in acute care often involves the contaminated hands or equipment of health care providers. Transmission between family members in the home setting has not frequently been reported.

Decolonization

Decolonization is not routinely recommended for colonized individuals. A decolonization protocol is available and may be used to attempt eradication of the bacteria from select patients.

The decolonization protocol consists of a ten-day course of Mupirocin ointment to both nares and daily showers (skin and hair) with a chlorhexidine soap.

Precautions

Always care for colonized patients using barriers to prevent transmission to other patients and health care staff. In the office, caregivers should wear gloves for all contact and wash hands immediately after glove removal. Avoid touching your face with contaminated hands to prevent accidental colonization of your own nares.

Equipment used for examination should be cleaned before use with another patient. This would include stethoscopes, thermometers, blood pressure cuffs, examination tables, etc. Stethoscopes and thermometers can be washed thoroughly and disinfected with 70% alcohol. Other equipment can be wiped with a hospital-grade disinfectant.

Primary care physicians may be asked to culture their patients for MRSA. Patients may have been identified as a contact of another patient with MRSA or a recheck of their current status may be required. Cultures are usually obtained from nares and groins in the following manner:

• moisten a cotton tipped culture swab (charcoal transport swab) with sterile saline or sterile water
• insert the swab into the anterior nares (< 1cm.) and gently rotate it
• using the same swab, repeat the procedure in the other nostril
• moisten a second cotton tipped swab as above
• roll or rub the cotton tip over the skin in the groin area
• using the same swab, repeat the procedure on the other groin

When completing the requisition, please note that the patient is an "MRSA contact" and request "aerobic culture for MRSA."