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Bullous impetigo
Other Resources UpToDate PubMed

Bullous impetigo

Contributors: Erin X. Wei MD, Molly Plovanich MD, Belinda Tan MD, PhD, Susan Burgin MD
Other Resources UpToDate PubMed


This summary discusses adult patients. Bullous impetigo in children is addressed separately.

Bullous impetigo is a superficial infection of skin typically caused by phage group II staphylococci and, less often, by other staphylococci phages. Additionally, there have been a few reports of beta-hemolytic streptococci causing bullous impetigo. The presentation of bullae is due to exotoxin-mediated cleavages of desmoglein-1.

It is primarily seen in children and does not commonly occur in teenagers or young adults. It presents as a painful eruption with fragile bullae and honey-colored crusting. Constitutional symptoms such as fever are rare and mild, if they occur. Staphylococcus aureus can secondarily infect the lesions of varicella, causing a bullous presentation. Disseminated bullous impetigo has been reported in patients with atopic dermatitis.

Infection is spread by direct contact with colonized or infected individuals. S aureus often colonizes the nares, umbilicus, nails, and eyes; approximately 5% of S aureus strains have exfoliative toxins. Outbreaks tend to occur during the summer months and in humid climates.

Methicillin-resistant S aureus (MRSA) first emerged as an important nosocomial pathogen in the 1960s. In more recent years, outbreaks of community acquired (CA)-MRSA have been described increasingly among healthy individuals lacking the traditional risk factors for such infections (eg, intravenous drug use, incarceration, participation in contact sports). The majority of purulent skin and soft tissue infections presenting to emergency rooms across the United States are caused by CA-MRSA.

Immunocompromised Patient Considerations:
Pyodermas (cutaneous bacterial infections) including impetigo are quite common in HIV-infected individuals. Additionally, pyodermas are found in immunosuppressed transplant patients, especially in the first months following transplant.

Recurrent bouts of impetigo are more common in immunocompromised patients. This may be due to persistent nasal carriage of S aureus, which has been reported to be as high as 50% in individuals with HIV.


L01.03 – Bullous impetigo

399183005 – Bullous impetigo

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Differential Diagnosis & Pitfalls

If persistent and recurrent, consider primary bullous diseases such as pemphigus vulgaris, bullous pemphigoid, epidermolysis bullosa acquisita, linear IgA dermatosis, and dermatitis herpetiformis.

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Last Reviewed:06/05/2022
Last Updated:07/06/2022
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Patient Information for Bullous impetigo
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Contributors: Medical staff writer


Impetigo is a common and contagious bacterial skin infection that is usually a minor problem, but sometimes complications may occur that require treatment. Complications related to impetigo can include deeper skin infection (cellulitis), infections of the brain, and kidney inflammation. Impetigo often starts with a cut or break in the skin that allows bacteria to enter. Impetigo is usually caused by "staph" (Staphylococcus) or "strep" (Streptococcus) bacteria. Impetigo can be further classified into 2 types: bullous and nonbullous.
  • Nonbullous impetigo accounts for 70% of all cases and appears as tiny fluid-filled blisters that develop into honey-colored, crusty lesions. Generally they do not cause any pain or redness to the surrounding skin.
  • Bullous impetigo appears as larger clear blisters filled with fluid. When these blisters break, they may leave a scale behind. Bullous impetigo is primarily seen in infants and children. It is less common in teenagers and young adults.

Who’s At Risk

Impetigo is very common in children, affecting up to 10% of those who come to a pediatric clinic. Children up to 6 years old are most likely to be infected. Impetigo also may occur in adults. Those who live in a warm, humid climate are more often affected. Insect bites, crowded living conditions, and poor skin cleansing make a person prone to infection. It may spread easily through schools and daycare centers. Participation in sports involving skin-to-skin contact, having a weak immune system, or having a chronic skin problem such as eczema also increases the chance of getting impetigo. Lesions on the neck and scalp may be associated with head lice.

Signs & Symptoms

  • Painless blisters (about an inch or less) occur that may break easily.
  • These often spread to the face, trunk, arms, or legs.
  • The person feels generally well (unless impetigo is severe).
Mild – There are only a few areas over a small and local area of skin, and the person feels well otherwise.

Moderate – There are over 10 spots, and several small skin areas are affected.

Severe – There are many lesions, large areas of skin are affected, and/or the person feels ill with fever, diarrhea, or weakness.

Self-Care Guidelines

Prevention is very important; keep the skin clean with soap and water. Treat cuts, scrapes, and insect bites by cleaning with soap and water and covering the area if possible.

For mild infection:
  • Gently wash the area with a mild soap and water twice or more daily, and cover with gauze or a non-stick dressing if possible.
  • An over-the-counter antibiotic ointment can be applied after washing the skin 3-4 times daily. Wash hands after application or wear gloves to apply.
  • To remove crusts, soak with a vinegar solution (1 tablespoon of white vinegar to a pint of water) for 15-20 minutes.
  • Wash clothing, towels, and bedding daily and don't share these with others.
  • Wash hands frequently, try not to touch the areas, and keep fingernails trimmed.

When to Seek Medical Care

Seek care for any infection that is not improving. If the infection is moderate to severe or there is fever or pain, seek medical attention.

If you are currently being treated for a skin infection that has not improved after 2-3 days of antibiotics, return to your doctor.

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is a strain of "staph" bacteria resistant to antibiotics in the penicillin family. CA-MRSA previously infected only a few people, such as health care workers and IV drug users. However, CA-MRSA is now a common cause of skin infections in the general population. While CA-MRSA bacteria are resistant to penicillin and penicillin-related antibiotics, most staph infections with CA-MRSA can be easily treated by health care practitioners using local skin care and commonly available non-penicillin-family antibiotics. Rarely, CA-MRSA can cause serious or deeper skin infections. Staph infections typically start as small red bumps or pus-filled bumps, which can rapidly turn into deep, painful sores. If you see a red bump or pus-filled bump on your skin that is worsening or showing any signs of infection (ie, the area becomes increasingly painful, red, or swollen), see your doctor right away. Many people believe incorrectly that these bumps are the result of a spider bite when they arrive at the doctor's office. Your doctor may need to test (culture) infected skin for MRSA before starting antibiotics. If you have a skin problem that resembles a CA-MRSA infection or a culture that is positive for MRSA, the doctor may need to provide local skin care and prescribe oral antibiotics. To prevent spread of infection to others, infected wounds, your hands, and other exposed body areas should be kept clean and wounds should be covered during therapy.


In addition to the treatments for mild impetigo already mentioned, either topical (usually mupirocin) or oral antibiotics (cephalosporins, amoxicillin, cloxacillin, dicloxacillin, erythromycin, or clindamycin) may be prescribed. If your doctor prescribes antibiotics, be sure to take the full course.
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Bullous impetigo
A medical illustration showing key findings of Bullous impetigo : Flaccid bullae, Painful skin lesions
Clinical image of Bullous impetigo - imageId=813507. Click to open in gallery.  caption: 'A close-up of a crusted erosion with a collarette of scale.'
A close-up of a crusted erosion with a collarette of scale.
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