Impetigo - Symptoms and Treatment

Impetigo is a bacterial skin infection that mainly affects children between 2 and 5 years old, although it can also occur in adults.

Impetigo is contagious and appears more often during hot summer months. In this paper we explain transmission, symptoms and treatment of impetigo.



Impetigo is a superficial skin infection that can be caused by two types of bacteria: Streptococcus pyogenes or Staphylococcus aureus.

Both bacteria normally live on our skin without causing us any harm. However, through a small wound, cut, or even a mosquito bite, they can reach the inner layers of the skin and cause infection.



Our skin is colonized by billions of bacteria, some of which are persistent colonizers while others are temporal ones. Generally our coexistence with these bacteria does not cause problems because the skin acts as a shield, preventing the counting of germs from the external environment with our inner environment. The infectious skin diseases generally arise when there is any injury that breaks this barrier of the skin, encouraging the entry of bacteria into the body.

Persistent colonizing bacteria are bacteria that live on our skin and are very difficult to be eliminated. However, this is not a problem, since this group is rarely able to cause disease even when there are skin lesions.

Temporary colonizing bacteria are the ones that are acquired from others by direct contact, staying on our skin only for a certain time. These are the bacteria that usually cause skin infections. The two bacteria that cause impetigo, Streptococcus pyogenes and Staphylococcus aureus, are also temporary colonizing bacteria. Furuncle, impetigo, ecthyma, folliculitis, cellulitis and erysipelas are examples of skin diseases caused by these bacteria.

The contamination by Streptococcus pyogenes or Staphylococcus aureus tends to be transmitted by direct contact of skin to skin, but can also occur through clothing, towels and toys to children.

Some patients contaminated with these bacteria can store them in the nasal cavity, making their elimination difficult, and they remain colonized for long. Even if the bacteria eliminate the skin, simple manipulating the nose with the hand can contaminate a person again.


There are 3 types of impetigo: common impetigo, bullous impetigo and ecthyma.

a.) Common impetigo

Common impetigo, also called non-bullous impetigo, is the most common. The table usually starts with small red papules similar to mosquito bites, which, however, are changing rapidly for small pustules (pus-filled lesions). These pustules burst and form lions crusted with golden or honey color. This process usually lasts for one week and lesions preferentially attack the face and / or skull, but may also arise in the arms and legs.

It is not common to have systemic symptoms such as fever or malaise, however, some painful lymph nodes in the neck often arise.

The lesions of impetigo usually do not hurt, but may cause itching. The scratching of the lesions may favor the spread of the disease by contaminated hands.

Over time the scabs disappear, leaving small red marks that disappear in the long term without leaving a scar.

b.) Bullous Impetigo

The Bullous impetigo is caused only by the bacteria Staphylococcus aureus, which is capable of producing toxins that cause detachment of the epidermis (outermost layer of the skin), favoring the appearance of blisters.

Bullous impetigo typically affects the upper and lower limbs and buttocks and trunk more frequently than the common impetigo. The bullous impetigo does not usually affect the face.

The initial lesion of bullous impetigo is equal to the common impetigo, with small papules, which, however, are changing rapidly for bubbles with yellowish content. The skin around the blisters is usually red and itchy. As in common impetigo, bullous impetigo lesions usually do not cause pain.

The blisters usually break up leaving a reddish-yellow crust, which is usually larger and more lasting than in the common impetigo. In bullous impetigo there may be fever and other symptoms of infection, such as malaise and loss of appetite.

The lesions usually heal well without consequences.

c). Ecthyma

The ecthyma is the most severe form of impetigo, since it affects the deeper layers of the skin. They are usually impetigo lesions that progress to the formation of skin ulcers that can drain pus. These ulcers usually develop into thick and yellowish crusts, with reddish margin, that heal slowly, leaving scars. It is not unusual to have fever at ecthyma.

The ecthyma affects most often the legs and can be caused by both Streptococcus pyogenes and Staphylococcus aureus.

Any of the three presentations of impetigo can complicate with rheumatic fever or glomerulonephritis. Another common complication is injury to the evolution of a cellulitis or erysipelas, more serious skin infections.


Impetigo is not usually a severe infection and often heals by itself. However, antibiotic treatment usually is indicated to decrease the chance of contamination of other people, hasten the resolution of lesions and decrease the risk of complications.

If injuries are very discreet, treatment can only be done with good hygiene and topical antibiotics. The most suitable is a mupirocin ointment (Bactroban) 3 times a day.

When the lesions are too widespread or if in case of bullous impetigo or ecthyma, treatment is usually done with oral antibiotics for 1 week. The most commonly used are derivatives of penicillin.