Impetigo Diagnosis

Learn about impetigo and how it's diagnosed. Download our free PDF template for easy reference.

By Telita Montales on Aug 2, 2025.

Fact Checked by Ericka Pingol.

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Types of impetigo infections

Impetigo is a common bacterial skin infection primarily caused by Staphylococcus aureus and Streptococcus pyogenes. This skin condition is especially notable for its contagious nature, often affecting children but also capable of impacting adults.

Non-bullous impetigo

Non-bullous impetigo is the most common form of this infection. It typically manifests as red sores that rapidly rupture, ooze, and develop a yellowish-brown crust. These sores often appear on the face, particularly around the nose and mouth, but can spread to other areas of the body through direct contact. The infection is highly contagious, making it essential for those affected to practice good hygiene to prevent the transmission of the disease.

Bullous impetigo

In contrast, bullous impetigo is less common and predominantly affects infants and young children. This type is characterized by large, painless, fluid-filled blisters that can develop on the trunk, arms, and legs. These blisters are more significant than those seen in non-bullous impetigo and may persist for a more extended period. Understanding the symptoms of bullous impetigo is vital for parents and caregivers to seek timely medical attention.

By recognizing these types of impetigo and their distinct characteristics, healthcare professionals can make a precise diagnosis and determine the most appropriate treatment approach, ensuring the best outcomes for those affected.

Impetigo Diagnosis Template

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Impetigo symptoms

Recognizing the symptoms of impetigo is crucial for timely diagnosis and treatment. Key symptoms include:

Red sores or blisters that rupture easily and ooze a clear fluid or pus.
Yellowish-brown crusts form over the sores after they burst.
Itchy sores that may cause discomfort and lead to scratching, which can spread the infection.
Swollen lymph nodes in severe cases.
Fever and general malaise in rare instances, particularly with extensive infections.

Symptoms typically appear on exposed areas of the skin, such as the face, arms, and legs. Early identification and treatment can prevent the spread and complications of impetigo.

Causes of impetigo infection

Impetigo is a bacterial infection caused by bacteria entering the skin through small cuts, insect bites, or other breaks in the skin. This skin infection is characterized by impetigo sores and painful blisters that can be distressing. Common causes include:

Bacterial entry

The primary culprits are Staphylococcus aureus and Streptococcus pyogenes, which can also lead to conditions like staphylococcal scalded skin syndrome. These bacteria thrive in warm, humid environments, making impetigo more common in summer and tropical climates.

Skin infection trauma

Minor injuries such as cuts, scrapes, or insect bites provide an easy entry point for these bacteria, potentially leading to impetigo blisters and crusted skin. Existing skin diseases or conditions, such as eczema or dermatitis, can increase the risk of developing impetigo, particularly in individuals with a weakened immune system.

Close contact with Staphylococcus aureus

Impetigo is highly contagious, spreading easily through direct contact with infected skin or contaminated objects. Close living conditions, such as those found in schools or daycare centers, facilitate the spread of impetigo among children, making awareness of its contagious nature crucial.

If left untreated, impetigo can lead to complications such as post-streptococcal glomerulonephritis, particularly in those with darker skin tones. Prompt topical treatment is crucial for managing symptoms and preventing the further spread of this bacterial skin infection.

How is impetigo diagnosed?

The diagnosis of impetigo is usually based on the characteristic appearance of the skin lesions. A physical examination by a healthcare provider is typically all that is needed for a diagnosis. In some cases, a sample of the affected skin may be taken and sent to a laboratory for analysis. This can help confirm the presence of bacteria or rule out other skin conditions.

In addition to examining the skin, the healthcare provider may also ask about any symptoms or recent exposure to others with impetigo. They may also check for signs of complications, such as swollen lymph nodes or fever.

It is important to note that impetigo can often be confused with other skin conditions, such as eczema or psoriasis. Therefore, a proper diagnosis by a healthcare provider is crucial in ensuring appropriate treatment.

In rare cases, a bacterial culture may be performed to determine the specific type of bacteria causing the impetigo infection and to identify the most effective antibiotics for its treatment. This is usually only done if the infection does not improve with initial treatment or if there are signs of a more serious infection.

What is the purpose of our handout?

We created a quick-reference handout to help healthcare providers identify the type of impetigo a patient may have. It’s designed for both experienced clinicians who want a convenient refresher and newer providers who are still building confidence in diagnosing skin infections.

To access our template, click the "Use template" button, allowing you to edit it via the Carepatron app. For a PDF copy, hit "Download."

Impetigo prevention and treatment options

Preventing and treating impetigo effectively involves a combination of good hygiene practices and appropriate medical interventions. Here are some key strategies to consider to prevent and treat it as well:

Good hygiene practices

To prevent the spread of infection, it is essential to wash your hands regularly with soap and water, especially after touching potentially contaminated surfaces. Keeping nails short and clean helps prevent scratching and the spread of infection. Additionally, avoid sharing personal items, such as towels, clothing, or bedding, as this can facilitate the transmission of bacteria.

Wound care

To minimize the risk of infection, it's essential to clean and cover any cuts, scrapes, or insect bites properly. Additionally, applying antiseptic ointments to minor skin injuries can help prevent bacteria from entering the wounds.

Isolation

Keep infected individuals away from school, daycare, or work until they are no longer contagious, thereby helping to protect others from infection.

Topical and oral antibiotics

Use topical antibiotics, such as mupirocin or fusidic acid, which can be applied directly to the affected area for localized infections, ensuring that the medication reaches the site of infection effectively. For more extensive or severe infections, prescribe patients oral antibiotics such as cephalexin or dicloxacillin to help combat the bacteria from within.

References

Diagnosis and treatment of impetigo. (2007, March 15). PubMed. https://pubmed.ncbi.nlm.nih.gov/17390597/

Hartman-Adams, H., Banvard, C., & Juckett, G. (2014, August 15). Impetigo: diagnosis and treatment. AAFP. https://www.aafp.org/pubs/afp/issues/2014/0815/p229.html

Commonly asked questions

Common skin infections that can be mistaken for impetigo include herpes simplex, fungal infections, and allergic dermatitis. A thorough clinical evaluation and laboratory tests help distinguish impetigo from these conditions.

Yes, insect bites can create broken skin that increases the risk of developing a skin infection like impetigo. When the skin barrier is compromised, bacteria such as Staphylococcus or Streptococcus can enter, leading to infection. It is crucial to treat insect bites properly to minimize the risk of secondary infections.

Healthcare professionals typically diagnose this common bacterial skin infection based on the characteristic sores and the patient's symptoms. They may also consider factors such as the presence of raw skin and any recent insect bites or skin injuries that could have allowed bacteria to enter. In some cases, they may use laboratory tests to confirm the diagnosis and determine the appropriate antibiotic ointment or oral antibiotic treatment if necessary.