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

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

24 September 2021

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

CA-MRSA patients and their close contacts (e.g. household contacts, boy/girlfriend, carer, etc.) should receive the following topical decolonization therapy (if there is no any contraindication):

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

  • Apply daily as liquid soap to whole body for 5 days; and
  • Apply as a shampoo to hair and scalp on days 1, 3 and 5.

Method of use: Apply to whole body, hair and scalp and leave for ONE minute before rinsing.

2. 10% povidone-iodine ointment (Betadine or other ointment containing the same active ingredient)

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

Method of use: Apply small amount of the ointment (about the size of a match head) to the inner surface of one nostril (anterior nare). Repeat the same for the other nostril. The nostrils are then closed by pressing the sides of the nose together using the thumb and the index finger. This can spread the ointment inside the nares. A swab may be used to assist the application of the ointment. The patient may feel the taste the ointment at the nasopharynx or back of the throat after application, which is normal.


  • The above decolonization therapy should be used by both the patient and close contacts as soon as possible after recovery of the current episode of CA-MRSA infection.

Information for Patients with Community-Associated Methicillin-Resistant Staphylococcus aureus (CA-MRSA) Infection and their close contacts


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

1. Maintain good personal hygiene

  • Perform hand hygiene frequently, especially before touching the mouth, nose or eyes; after touching public installations such as handrails or door knobs; or when hands are contaminated by respiratory secretion after coughing or sneezing.
  • Wash hands with liquid soap and water, and rub for at least 20 seconds. Then rinse with water and dry with a disposable paper towel or hand dryer. If hand washing facilities are not available, or when hands are not visibly soiled, hand hygiene with 70 to 80% alcohol-based handrub is an effective alternative.
  • Wear gloves when handling soiled objects, and perform hand hygiene 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 wound immediately and cover it properly with waterproof adhesive dressings until healed.
  • Perform hand hygiene 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. Proper use of antibiotics

  • Do not demand antibiotics from your doctor.
  • Follow your doctor’s advice when taking antibiotics.
  • Do not stop taking antibiotics by yourselves even if you are feeling better.
  • Do not take leftover antibiotics.
  • Do not share your antibiotics with others.
  • Enhance personal hygiene while you are taking antibiotics to protect yourself and to prevent the spread of bacteria:
    • Practise frequent hand hygiene.
    • Eat or drink only thoroughly cooked and boiled items.
    • Disinfect and cover all wounds.
    • Wear a surgical mask if you have respiratory symptoms like cough, sneeze, runny nose and sore throat.
    • Young children with symptoms of infections should minimise contact with other children.

4. Maintain good 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 more information on the use of bleach, please visit the following webpage:

Other languages

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

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