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

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

9 May 2017

Causative agent

Staphylococcus aureus (S. aureus) is a bacterium commonly carried on the skin or in the nasal cavity of healthy people. These healthy individuals carry the bacteria without signs or symptoms of infection. Yet, the bacteria may sometimes cause diseases such as infection of skin, wound, urinary tract, lung, bloodstream and food poisoning.

Most S. aureus infections can be treated by antibiotics effectively. However, methicillin-resistant S. aureus (MRSA) is a strain of S. aureus that is resistant to antibiotics including methicillin and other commonly used antibiotics such as oxacillin, penicillin, amoxicillin and cephalosporins. Improper use of antibiotics is widely recognised as a contributing factor to antibiotic resistance.

Most MRSA infections occur in people who have been hospitalised, live in residential care homes or have received treatment in health care settings such as dialysis centres. However, infections can also occur in community-dwelling individuals who have not been hospitalised, stayed in residential care homes, or received medical procedures within a year prior to symptom onset. These are known as community-associated MRSA (CA-MRSA) infections.

Clinical features

CA-MRSA usually causes skin and soft tissue infections such as pimples, boils, abscesses or wound infections. The infected area may be red, swollen and painful or it may produce pus. Sometimes, more serious sequelae such as bloodstream infections, lung infections or necrotising fasciitis may occur.

Mode of transmission

The main mode of transmission of CA-MRSA infections is through direct contact with wounds, discharge and soiled areas. Other risk factors include close contact, presence of skin lesions such as cuts or abrasions, contact with soiled items, poor personal hygiene and crowded living conditions.


Individuals with wound infection should seek advice from healthcare professional quickly so that the infection can be properly diagnosed and effectively treated. Boils or abscesses may require incision and drainage and antibiotics may be prescribed if indicated. For patients with confirmed CA-MRSA infection, doctors may offer decolonization therapy (please refer to “Decolonization therapy” below) as appropriate (e.g. if no contraindication).

Decolonization therapy

The decolonization therapy contains the following two medications for external use:

1. 4% chlorhexidine gluconate liquid soap (Hibiscrub or other product containing the same active ingredient)

Apply daily as liquid soap to whole body for 5 days, and as a shampoo to hair and scalp on days 1, 3 and 5. Leave for ONE minute before rinsing.


2. 2% mupirocin nasal ointment (Bactroban or other product containing the same active ingredient)

Three times daily application for 5 days into anterior nares of both nostrils.

In general, decolonization therapy should be started after the skin and soft tissue infection has resolved. Decolonization medications are for external use only and are not routinely recommended for children under 12 years of age.

Information for patients with CA-MRSA infection


The following measures may help protect against CA-MRSA infections:

1. Maintain personal hygiene

  • Wash hands with liquid soap and water thoroughly when they are visibly soiled or likely dirtied by body fluid. When hands are not visibly soiled, clean them with 70 - 80% alcohol-based handrub as an effective alternative.
  • Wear gloves when handling soiled objects, and wash hands thoroughly afterwards.
  • Avoid sharing personal items such as towels, clothing or uniforms, razors or nail-clippers.

2. Proper wound management

  • Avoid direct contact with wounds or objects soiled by wound discharge.
  • Clean broken skin immediately and cover it properly with waterproof adhesive dressings. Wash hands before and after touching wounds. Consult doctor promptly if symptoms of infection develop.
  • Avoid contact sports or visiting public bathrooms if you have an open wound.

3. Safe use of antibiotics

  • Only take antibiotics prescribed by your doctor.
  • Follow advice given by your doctor when taking antibiotics.
  • Enhance personal hygiene while you are taking antibiotics to protect yourself and to prevent the spread of bacteria:
    • Keep hands clean.
    • Eat only well-cooked food. Drink only boiled water.
    • Disinfect and cover all wounds.
    • Wear a surgical mask if you have respiratory symptoms like cough, sneeze, runny nose and sore throat.
    • Young children having symptoms of infection should minimise contact with other children.
  • Never share your antibiotics with others.

4. Maintain environmental hygiene

  • Keep the environment clean; disinfect reusable items in public places such as sports centres and public bathrooms regularly.
  • CA-MRSA can spread among family members via contaminated household items. It is important to keep the home clean and free of dust. Frequently-touched surfaces (e.g. toilet seat, bathroom), children’s toys and bed linens should be washed, cleaned and disinfected (with diluted household bleach) regularly. For the correct method of using bleach, please browse the following webpage:

Other languages

Methicillin-resistant Staphylococcus Aureus (MRSA) Infection and Community-associated MRSA Infection (Pamphlet):

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