Mycoplasma pneumoniae infection

Causative agent

This infection is caused by the bacterium Mycoplasma pneumoniae. Mycoplasma pneumoniae infection can occur at any time of the year. Community outbreaks may occur every 3 to 7 years.

Clinical features

Mycoplasma pneumoniae causes acute respiratory illness. The majority of patients present with mild upper respiratory tract symptoms, such as fever, cough, sore throat, malaise and headache. Only 5 to 10% of infected patients develop atypical pneumonia. It is one of the most common causes of community-acquired pneumonia in otherwise healthy patients younger than 40 years. Although Mycoplasma pneumoniae infection usually causes mild illness, severe complications such as severe pneumonia, encephalitis, renal impairment, and haemolytic anaemia may occur in some patients, especially elderly or immunocompromised persons.

Mode of transmission

Mycoplasma pneumoniae mainly spreads from person to person through respiratory droplets of infected persons when they cough or sneeze. It may also be spread by direct contact with the nose or throat discharges of an infected person; or indirectly through contact with articles freshly soiled by secretions of infected persons.

Incubation period

The incubation period ranges from 2 to 3 weeks.

Management

Most people recover from mild infection spontaneously. For pneumonia or severe infection, patients will be treated with antibiotics.

Prevention

There is no vaccine against Mycoplasma pneumoniae available at the moment. As a general measure to prevent respiratory diseases, the members of public are advised to:

• The wearing of mask is advised for the following situations - 
  • any persons with fever or respiratory symptoms;
  • any persons who are visiting or working in high risk places such as residential care homes for the elderly, residential care homes for persons with disabilities, and clinical areas of healthcare facilities; and
  • high risk persons (e.g. persons with underlying medical conditions or persons who are immunocompromised) who are going to crowded places such as public transport.
  • When an increasing trend in activity of respiratory viruses is expected, high risk persons are recommended to wear a surgical mask when visiting public places, while the public should also wear a surgical mask when taking public transportations or staying at crowded places.
• It is important to wear a mask properly, including hand hygiene before wearing and after removing a mask. For details on proper mask wearing, please visit CHP website at www.chp.gov.hk/files/pdf/use_mask_properly.pdf;
• Perform hand hygiene frequently, especially before touching one’s mouth, nose or eyes; before eating; after using the toilet; 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.
• Cover your mouth and nose with tissue paper when sneezing or coughing. Dispose of soiled tissues into a lidded rubbish bin, then wash hands thoroughly.
• When having respiratory symptoms, wear a surgical mask, refrain from work or attending class at school, avoid going to crowded places and seek medical advice promptly.
• Build up good body immunity by having a balanced diet, regular exercise, adequate rest, reducing stress, do not smoke and avoid alcohol consumption.
• Infected person should avoid contact with children, the elderly or those with weakened immunity.

• Regularly clean and disinfect frequently touched surfaces such as furniture, toys and commonly shared items with 1 in 99 diluted household bleach (mixing 10 ml of household bleach containing 5.25% sodium hypochlorite with 990 ml of water), leave for 15 to 30 minutes, and then rinse with water and keep dry. For metallic surface, disinfect with 70% alcohol.
• Use absorbent disposable towels to wipe away obvious contaminants such as respiratory secretions, and then disinfect the surface and the neighbouring area with 1 in 49 diluted household bleach (mixing 10 ml of household bleach containing 5.25% sodium hypochlorite with 490 ml of water), leave for 15 to 30 minutes and then rinse with water and keep dry. For metallic surface, disinfect with 70% alcohol.
• Maintain good indoor ventilation.
• Avoid going to crowded or poorly ventilated public places; high-risk individuals may consider wearing a surgical mask when staying in such places.