Last updated on May 5, 2021.
Impetigo causes red sores and lesions all over the body, which can itch and sometimes be painful. It is a common bacterial skin infection among paediatric population, making up about 10% of childhood skin problems. Here is an expert guide to impetigo, reviewed by paediatrician Dr. Eddie Cheung.
What is impetigo?
It is an extremely contagious infection of the skin that results in blisters and sores. They can be found anywhere, but mostly around the nose and mouth, limbs and the diaper area. It is generally not a serious disease and normally resolves in 7-10 days with proper treatment.
Impetigo particularly affects children between 2 and 5 years old. It is also more common in warm and humid environments, like summers in Hong Kong. Your doctor will diagnose a child by examining the affected skin area or collecting blister fluid for bacteria culture.
Two types of bacteria cause impetigo, namely Staphylococcus aureus and Group A Streptococcus (less common). Broken skin such as cuts and insect bites, or skin conditions for example eczema allows bacteria to invade and cause impetigo. These bacteria can also infect normal and healthy skin.
Impetigo can be classified into the following:
- Bullous: causes pus-filled blisters. The fluid inside becomes more cloudy with time. It tends to affect torso more.
- Non-bullous: the most common form (70% of all cases). It forms a distinctive honey-coloured crusts, usually involving face, arms and legs.
- Ecthyma: a more serious form of impetigo that causes ulcers.
Incubation period: 1-3 days for Group A Streptococcus infection, and 4-10 days for Staphylococcus aureus infection.
Infectious period: Until sores have healed or 48 hours after the start of the antibiotic treatment.
Children with impetigo should not go to nursery or school until the end of the infectious period.
How is impetigo transmitted?
Impetigo spreads easily through close contact with infected people even if they do not have visible lesions. Therefore, family members and friends are at greater risk. Children can spread the infection to other parts of their skin if they scratch it.
People can also get impetigo by touching or sharing items that have been touched by someone who has the infection, for example clothes and towels.
Signs and symptoms of impetigo
Depending on the types of impetigo, they have different signs and symptoms. A fever is usually not present.
Non-bullous impetigo (crusted)
The lesions start as red-edged bumps that are filled with fluid. These blisters get bigger in size and rupture rapidly and easily, oozing and leaving golden crusts on the skin. The scabs then fall off without scarring. Non-bullous impetigo is mildly itchy and sometimes painful. The sores tend to develop on the face and extremities.
Bullous impetigo (blisters)
It is characterized by painless large blisters containing clear yellow fluid that gradually turns darker in colour. These blisters stay on the skin longer and are followed by the formation of a thin brown scab. The chest, belly and the back are mostly affected. Bullous impetigo causes less lesions than the non-bullous one.
It causes ulcers that penetrate deep into the skin. They cause deeper erosions with yellow crusts and red rims. Scars can be seen as it heals.
When should you see a doctor?
Consult your doctor if your child shows signs and symptoms of impetigo, is not responsive to treatment, if the condition worsens or if there is a fever.
You should also take your child to see a GP if they have had impetigo that recurs frequently.
How is impetigo treated?
Your doctor will recommend different treatments based on the type and the severity of your child’s impetigo.
Your child will be given antibiotic ointment or cream if they only have a small infected skin area. Apply three times daily after cleaning and removing the scabs for 5 days. Topical antibiotics have fewer side effects than the oral ones. Examples include mupirocin ointment and fusidic acid cream.
It is important to take all the antibiotics as prescribed by your doctor even if the sores are clearing up.
- Keep your child’s fingernails clipped to avoid touching or scratching. The bacteria can get on hands and be transferred to everything touched.
- Gently clean the skin and remove the crusts with water and soap every day.
- Cover the sores and blisters with a gauze or a loose bandage until they heal to prevent spreading to other body parts or to other people.
Good personal hygiene is the key in staying away from and spreading all kinds of infections, including impetigo. Always remember to practice the following points:
- Wash your hands regularly with soap and water or use an alcohol-based hand sanitizer, especially right after touching the infected person and items they are in contact with.
- Use hot water to wash and high heat to dry clothing, towels and bed linens.
- Clean frequently touched surfaces and your child’s toys with disinfectant and warm water.
- Do not share any personal items.
- Do not go to the gym or participate in sports that require physical contact.
Dr. Eddie Cheung 張蔚賢醫生 is a specialist in paediatrics. He received his paediatric training in Queen Mary Hospital and post-fellow paediatric cardiology training in Grantham Hospital/ Queen Mary Hospital. He is a Fellow of the Hong Kong College of Cardiology, the Vice President of Hong Kong Society of Paediatric Cardiology and Consultant of Hong Kong Association of Cleft Lip and Palate. He is currently working as Director of Paediatric Centre of HK Medical Consultants and serves as Infection Control Officer at the Hong Kong Adventist Hospital.