Community associated-Methicillin-resistant
Staphylococcus aureus (CA-MRSA) Infection

Causative agent

Staphylococcus aureus is a bacterium commonly found on human skin and mucosa. About a third of normal healthy people may carry this bacterium in the nose or on skin without infection. Occasionally, this bacterium gets into the body and causes disease, such as skin infection, wound infection, food poisoning, urinary tract infection, pneumonia and infection of blood stream.

Most strains of Staphylococcus aureus are sensitive to many antibiotics and infections can be effectively treated. However, those strains that are resistant to the antibiotic methicillin (methicillin-resistant Staphylococcus aureus, MRSA) are usually also resistant to other commonly used antibiotics such as penicillins and cephalosporins. It is widely recognized that indiscriminate use of antibiotics may contribute to antibiotic resistance.

In the past, MRSA infections commonly occurred in institutionalized persons and hospitalized patients. In recent yeas, many countries observe MRSA infections in healthy individuals who have not been hospitalized or stayed in other healthcare facilities or institutions, nor received medical procedures in the past one year prior to symptom onset. They are known as community associated-MRSA (CA-MRSA) infections and usually have different patterns of antibiotic resistance. The medical profession concerns about the emergence of CA-MRSA.

Clinical features

CA-MRSA commonly causes skin or soft tissue infections (pimples, boils or abscesses). Symptoms may include redness, warmth, swelling, skin tenderness or pus drainage. And sometimes more serious effects such as purulent wound infections and severe pneumonia may occur, requiring hospitalisation and special antibiotics for treatment.

Mode of transmission

The main mode of transmission of MRSA infections is direct contact with wounds, discharge and soiled areas, usually via hands which may then contaminate other body sites, items or surfaces. Risk factors include close body contact, presence of openings in the skin such as cuts or abrasions, crowded conditions, and poor personal hygiene. The bacteria can be carried by healthy individuals, usually in nasal cavity, hair and armpit regions, and these carriers may pass the bacteria to other people.

Management

CA-MRSA infected skin lesions such as boils or abscesses may require incision and drainage while antibiotic treatment may be prescribed if indicated. Personal hygiene especially hand hygiene and proper handling of nasal discharge and care for skin wounds with appropriate dressing are of paramount importance. Personal and hand hygiene are particularly important for individuals taking antibiotics, as loss of normal bacterial flora during this time predisposes even healthy individuals to acquiring CA-MRSA.

Prevention

1. Maintain good personal hygiene.
2. Keep hands clean by washing thoroughly and frequently with liquid soap and water, or by rubbing them properly with alcohol handrub.
3. Wear gloves whenever it is necessary to touch grossly soiled objects, (e.g. saliva, pus discharge of other household members or pets), and wash hands thoroughly afterwards. This is especially important for immunocompromised persons.
4. Avoid sharing personal items such as unlaundered towels, clothing or uniforms and razors.
5. Avoid direct contact with wounds or anything contaminated by wound secretions.
6. Clean any broken skin such as abrasions or cuts immediately and cover properly with waterproof adhesive bandages. Wash hands before and after touching wounds. Consult a doctor promptly if symptoms of infections develop.
7. Avoid contact sports and visiting public bath houses if you have an open wound.
8. Maintain environmental cleanliness and sterilize reused equipments in public places such as sports center and public bathroom.
9. Do not take antibiotics indiscriminately. Antibiotics should be prescribed by registered medical practitioners and the patient should complete the whole course of treatment according to the prescribed dosage and frequency.
10. Observe strict hand hygiene and wear mask (for those with respiratory symptoms) if individuals are taking antibiotics.

Centre for Health Protection Website: www.chp.gov.hk
24-Hour Health Education Hotline of the Department of Health 2833 0111.