What causes impetigo on the cheek

Purulent vesicles and yellow crusts


Purulent vesicles and yellow crusts

By Brigitte M. Gensthaler


Impetigo contagiosa is the most common bacterial skin infection in children. Since the disease is highly contagious, it spreads quickly in kindergartens and schools. Good for the little ones: With consistent therapy, impetigo heals without scars.


Lichen, bark and pustular lichen or train: The popular names are indicative of the unpleasant skin infection that usually occurs on the face, on the hairy scalp or on the hands and legs. The ear canal or nasal mucosa can also be affected. Characteristic are watery, purulent skin vesicles that burst quickly and leave honey-yellow crusts behind.


Impetigo is always caused by bacteria. According to the Robert Koch Institute (RKI) in Berlin, 80 percent of the triggers are β-hemolytic streptococci of serogroup A, for example Streptococcus pyogenes. Staphylococcus aureus is detected in around 20 percent of patients. Often both germs cavort in the lesions. The natural location of Staphylococcus aureus is the nasal mucosa and the perianal region. Only 15 to 20 percent of the healthy population never carry the germs in their noses. Streptococcus pyogenes does not occur on healthy skin, but is occasionally detectable in the throat of healthy test persons.


The pus pathogens are highly infectious and are usually transmitted by smear infection through direct skin contact between people. Indirect infection through infected objects such as clothing, toys, towels or combs is also possible. This explains why the infection often spreads very quickly in families, children's groups, and schools. A child can also infect themselves, for example through their infected nasal secretions. According to a study, the peak of the disease is between three and eight years. Impetigo is rare in adults.


The superficial infection can affect healthy skin. However, this happens particularly easily when the physiological skin barrier is disturbed, for example in the case of injuries, chronic eczema and neurodermatitis. The incubation period is very variable and can range from one day to several weeks. In most cases it is two to ten days.


Highly infectious vesicles


Basically, a distinction is made between a non-bullous and a small and large blistered form of impetigo contagiosa. In non-bullous impetigo, the patients have no vesicles, only honey-colored to brownish crusts on a reddish background. This clinical picture can also be found in a secondary infection of existing skin lesions, which is known as impetiginization.


The small-bubble shape is caused by streptococci, while staphylococci are responsible for the large-bubble shape. The lichen planus begins with the formation of small blisters and pustules, which burst very quickly in the small-blistered form. In the large bubble shape, the bubbles can be 1 to 2 cm in size. When it bursts, a transparent to yellowish, purulent liquid is emptied, which dries up and leaves honey-yellow to brownish crusts behind. These lie on reddened skin and are sharply defined.


Individual strains of Streptococcus pyogenes can cause secondary kidney damage. Urinalysis helps detect glomerulonephritis early. With staph infections, itching, fever, or swelling of the lymph nodes can occasionally occur. Impetigo rarely affects the deeper layers of the skin or the nail bed and nail fold. The diagnosis is easy for the pediatrician because the clinical picture is so typical. The pathogen can be identified by a bacteriological examination of the bladder fluid or a nasopharynx swab. The nasal swab is also recommended if children have repeated illnesses.


Local therapy is rarely enough


According to the guidelines of the German Dermatological Society (DDG) and the Working Group for Dermatological Infectious Diseases (ADI), only minor staphylococcal infections can be treated topically. In the case of streptococcus infestation, the children should always receive antibiotics systemically.


Some paediatricians advocate local therapy alone for localized, uncomplicated or already healing infections. If the body is affected over a large area, in several places at the same time or in critical regions such as the ear canal or the corners of the eye, they prescribe systemic antibiotics. The same applies if the child has a weakened immune system, feels ill and has a fever, recurrences occur after purely topical therapy or a mixed infection is present.


Ointments, creams and solutions with antibiotics such as fusidic acid, tyrothricin and mupirocin or with antiseptics such as chlorhexidine, clioquinol, quinolinol sulfate, polyvidone iodine, ethacridine lactate or octenidine are suitable for topical therapy. The increasing resistance rate of Staphylococcus aureus to fusidic acid is problematic. There is practically no resistance to mupirocin in Germany. The nasal ointment is a reserve drug for eradicating MRSA (methicillin-resistant Staphylococcus aureus) in the nose.


Give antibiotics systemically


DDG and ADI still recommend penicillin as the first choice for streptococcal infections (example: Penicillin V peroral). If you are allergic to penicillin, you can switch to first-generation cephalosporins (example: cefalexin), macrolides (example: roxithromycin) or clindamycin. However, resistance to macrolide antibiotics is increasing.


Staphylococcal infections are treated with beta-lactamase-resistant penicillins (examples: flucloxacillin, dicloxacillin) or first-generation cephalosporins, amoxicillin / clavulanic acid or clindamycin. Before starting therapy, a so-called antibiogram should be carried out, a plate diffusion test to determine the sensitivity of germs to antibiotics. The medical societies demand that the therapy should be adapted to the antibiogram. In the case of mixed infections, beta-lactamase-solid penicillins or cephalosporins are used.


Patients are infectious until all open, purulent skin areas have healed. According to the Infection Protection Act, children with impetigo are not allowed to visit community facilities such as kindergartens or crèches. This is possible again at the earliest 24 hours after the start of an effective antibiotic therapy or after all infected skin areas have healed, informs the RKI. A written medical certificate is required for this.


Prevent smear infection


Since the infection is transmitted and maintained by scratching and skin contact, general measures can promote healing and interrupt the chain of infection. By bandaging or covering the lesions, the parents can prevent further smearing of the infectious vesicle fluid. The sick child and all contact persons should wash their hands frequently, in any case after every skin contact with the child. His fingernails should be cut as short as possible. This also reduces the germ reservoir under the fingernails. Thorough washing with acidic syndets or special washing solutions disinfects the skin.


The little patient is not allowed to bathe with other children and absolutely needs a towel, washcloth and comb for himself. Parents should explain why this is necessary to siblings so that they understand why they are not allowed to use the sick child's towel. Clothing and bed linen contaminated with bacteria should be changed frequently and washed at 60 to 90 ° C if possible.


Impetigo is highly contagious and looks ugly. But with consistent therapy, it heals without scars and consequential damage. Careful skin care and hygiene can largely prevent new infections.