Understanding Impetigo: Causes, Symptoms, Treatment, and Prevention

Impetigo is a highly contagious skin infection caused by bacteria known as Staphylococcus aureus and Streptococcus pyogenes. It predominantly affects children but can also occur in adults. This condition is especially prevalent in warm, humid environments and among groups in close contact, making it a significant concern in schools and childcare settings. Characterized by red sores that quickly rupture and form honey-colored crusts, impetigo can cause discomfort and lead to more serious health issues if not properly treated.

A systematic review highlighted its global impact, noting a median prevalence of 11.2% among children in various studies. This indicates a considerable burden in many regions, especially in resource-limited settings. This underscores the importance of understanding, preventing, and managing impetigo to mitigate its effects on health and well-being.

In this article, you will learn about the definition and types of impetigo, its causes and risk factors, symptoms, how it's diagnosed, treatment options, strategies for prevention, and possible complications for managing and understanding this skin infection.

Source: CDC

Impetigo is a bacterial skin infection that generally manifests as reddish sores around the nose and mouth, on the hands and feet, and can spread to other body parts. These sores burst and form a distinctive honey-colored crust. The condition is primarily caused by Staphylococcus aureus and Streptococcus pyogenes, individually or in combination. It's known for its high contagion and mainly affects infants and young children, although it can occur in people of any age.

Impetigo is categorized into these different forms:

• Non-bullous Impetigo: This is the most common form. It typically starts with red sores that burst near the nose and mouth, leaving a yellow, honey-colored crust. The sores may spread to other areas through touch or sharing items like towels.
• Bullous Impetigo: Caused by a toxin produced by Staphylococcus aureus, this form results in larger blisters or bullae, especially on the trunk, arms, and legs. These blisters can break open, revealing red, moist skin that may ooze or become crusted.
• Ecthyma: This is a more severe form of impetigo that penetrates deeper into the skin, causing painful fluid- or pus-filled sores that turn into deep ulcers, potentially leaving scars.

Each type of impetigo has distinct characteristics but generally starts from minor cuts, insect bites, or any form of skin breakage that allows bacteria to invade and infect the skin. Non-bullous impetigo often presents with minimal to no surrounding redness and can spread rapidly, sometimes leading to "kissing lesions" where two skin surfaces touch. In contrast, bullous impetigo may include symptoms like fever, malaise, and lymphadenopathy due to the systemic effects of the toxins produced by the bacteria.

Impetigo's clinical presentation can vary slightly depending on the skin tone, with the initial red marks (erythematous macules) potentially harder to detect on darker skin. Regardless of the type, impetigo can cause significant discomfort and has the potential to spread if not properly managed.

2. Causes and Risk Factors

Impetigo is primarily caused by a bacterial infection, most commonly Staphylococcus aureus or Streptococcus pyogenes. These bacteria can invade the skin directly or gain entry through minor cuts, scrapes, insect bites, or any disruption to the skin's protective barrier. Once inside, they proliferate and cause the characteristic sores and lesions associated with impetigo.

The major causes that allow these bacteria to infect the skin are as follows:

• Direct Bacterial Invasion: A compromised skin barrier allows S. aureus or S. pyogenes to colonize and infect the skin, leading to impetigo.
• Secondary Infection: Impetigo can develop as a secondary infection in individuals with pre-existing skin conditions like eczema, chickenpox, or insect bites that have disrupted the skin's integrity.

Several risk factors increase an individual's susceptibility to developing impetigo:

• Age: Children between 2 and 5 years old are most susceptible, likely due to close contact in school or daycare settings and frequent minor skin injuries.
• Close Contact: The infection spreads easily through direct skin-to-skin contact within families, schools, childcare facilities, or during sports involving physical contact.
• Warm, Humid Environments: These conditions promote bacterial growth and increase the risk of impetigo.
• Compromised Skin Barrier: Cuts, scrapes, insect bites, or any form of skin damage can be entry points for bacteria.
• Underlying Skin Conditions: Individuals with eczema or other dermatological conditions that affect the skin's barrier are at higher risk.
• Weakened Immune System: Factors like stress, chronic illnesses, or malnutrition can impair the immune system's ability to fight infections, including impetigo.

Impetigo is highly contagious and can spread through contact with infected sores or indirectly via contaminated surfaces, such as towels, clothing, or toys. While stress does not cause impetigo, it can weaken the immune system, making the skin more vulnerable to bacterial infections.

3. Symptoms

Impetigo symptoms vary depending on the type of impetigo but generally include the development of red sores or blisters that can burst and form a honey-colored crust. The sores are often itchy and can be painful.

For non-bullous impetigo, which is the most common form, the symptoms typically begin with tiny blisters that eventually rupture and develop into the following:

• Small wet patches of red skin that may ooze fluid.
• Gradually, a tan or yellow-brown crust covers the affected area, making it look like it has been coated with honey or brown sugar.

In the case of bullous impetigo, the condition manifests with larger, fluid-filled blisters that exhibit these characteristics:

• The blisters are filled with a clear fluid that may become cloudy.
• These blisters can appear on unaffected skin and are more likely to affect the trunk or diaper area in young children.
• After the blisters burst, they leave a raw, red area that may weep fluid.

Ecthyma, a more severe form of impetigo, presents with deep, painful sores that develop in the following manner:

• Fluid- or pus-filled sores that penetrate deeper into the skin, forming ulcers.
• The ulcers have a hard crust and can be very painful.
• Ecthyma can lead to scarring once the sores heal.

Across all types of impetigo, some general symptoms may include:

• Redness around the sores.
• Swollen lymph nodes near the affected area.
• Itching and soreness, although generally mild, can accompany the lesions.

It's important to note that impetigo can spread to other body areas through touch, clothing, and towels. Scratching the affected area can also spread the bacteria to different parts of the body or other people.

4. Diagnosis

The diagnosis of impetigo typically involves a healthcare provider's visual examination of the skin. Since the symptoms of impetigo are quite distinctive, especially the honey-colored crusts of non-bullous impetigo and the large blisters of bullous impetigo, a medical professional can often diagnose the condition based on its appearance alone.

The diagnostic process for impetigo may include the following steps:

• Visual Examination: A healthcare provider will examine the sores. The characteristic appearance of impetigo lesions is usually enough to diagnose the condition.
• Culture Test: A doctor may perform a culture test if the diagnosis is unclear or the impetigo is recurrent or particularly resistant to treatment. This involves taking a sample from the blister or sore and sending it to a laboratory to identify the bacteria causing the infection. This test can help determine the most effective antibiotic for treatment.
• Skin Swab: For recurrent infections, skin swabs can also help identify whether the person is a carrier of staphylococcal or streptococcal bacteria, particularly in the nose. This can influence treatment decisions to prevent further recurrence.
• Nasal Swabs: In cases of recurrent impetigo, the patient's nasal swabs and close contacts may be performed to identify carriers of the causative bacteria.

While impetigo has a distinct appearance, healthcare providers may consider other potential diagnoses with similar symptoms:

• Eczema: Especially when it's infected.
• Herpes Simplex: Due to its vesicular appearance.
• Contact Dermatitis: When there's a history of exposure to irritants.
• Fungal Infections: Given their potential to cause rash and itching.

5. Treatment Options

Impetigo treatment aims to heal the sores, improve skin appearance, prevent the infection from spreading, and avoid potential complications. The approach to treatment depends on the type of impetigo and the severity of the infection.

Topical Antibiotics

For mild cases of non-bullous impetigo, topical antibiotics are often the first line of treatment. Impetigo medications such as mupirocin (Bactroban) or fusidic acid cream are applied directly to the sores after gently cleaning the affected area. These topical treatments can effectively eradicate the bacteria causing the infection, typically within a week.

Oral Antibiotics

More severe cases of impetigo or where large body areas are affected may require oral antibiotics. Oral antibiotics are also used if the infection doesn't respond to topical treatments. Commonly prescribed antibiotics include flucloxacillin, erythromycin, or cephalexin. The course usually lasts 7 to 10 days, depending on the antibiotic used and the response to treatment.

Supportive Care

In addition to antibiotic treatment, supportive care measures can help manage symptoms and prevent the spread of impetigo:

• Gentle Cleansing: Regularly washing the affected areas with soap and water to remove crusts and discharge.
• Hygiene Measures: Maintaining good personal hygiene, including handwashing with soap and water, reduces the risk of spreading the infection.
• Avoiding Scratching: Keeping fingernails short and clean to prevent scratching and spreading the infection to other parts of the body or individuals.
• Isolation Measures: Keeping affected children away from school or daycare until they are no longer contagious, usually 24 hours after starting antibiotic treatment.

It's important for individuals undergoing treatment for impetigo to complete the full course of prescribed antibiotics, even if the sores heal before the medication is finished. This ensures the bacteria are completely eradicated and reduces the risk of recurrence or resistance.

6. Prevention Strategies

Preventing impetigo involves measures to reduce the risk of infection and its spread. The key prevention strategies can be categorized into the following areas:

Personal Hygiene

Maintaining good personal hygiene practices is crucial in preventing the spread of impetigo. These practices include:

• Frequent handwashing with soap and water, especially after touching affected areas.
• Promptly cleaning and covering any cuts, scratches, or insect bites to prevent bacterial infection.
• Encouraging children and adults to avoid touching sores or blisters on themselves or others.

Environmental Hygiene

Keeping the environment clean and avoiding sharing personal items can help prevent the transmission of impetigo. Specific measures involve:

• Not sharing personal items such as towels, bedding, and clothing with someone infected with impetigo.
• Washing clothes, linens, and towels of an infected person separately in hot water with detergent, and drying them in high heat.

Managing Contacts

Limiting contact with infected individuals and informing close contacts about potential exposure can help control the spread of impetigo. This includes:

• Isolating infected individuals by having them stay home from school, daycare, or work until they are no longer contagious, usually 24 hours after beginning antibiotic treatment.
• Informing those who have been in close contact with someone diagnosed with impetigo, so they can take preventive measures.

Monitoring and Managing Skin Conditions

Proper management is essential for individuals with underlying skin conditions that increase the risk of impetigo. Strategies in this area involve:

• Effectively controlling eczema or other skin conditions that break the skin's barrier reduces the risk of developing secondary impetigo.
• Regularly checking the skin of children and adults for signs of impetigo, especially during warm months or if they are in close contact environments.

Despite these preventive measures, impetigo can still occur. Early treatment and adherence to prescribed medications are essential to control the spread of impetigo and minimize complications.

7. Complications of Impetigo

While impetigo itself is usually not serious and tends to resolve with appropriate treatment, if left untreated or not adequately managed, it can lead to complications, some of which can have long-term effects. The potential complications can be categorized as follows:

Skin Complications

Impetigo can sometimes progress and affect the deeper layers of the skin, resulting in more severe skin issues. These include:

• Cellulitis: This deeper skin infection can occur if the bacteria from impetigo spread beneath the skin's surface. Cellulitis requires prompt medical treatment, often with oral or intravenous antibiotics, to prevent further spread that could reach the bloodstream.
• Scarring: Particularly with ecthyma, the more severe form of impetigo that affects deeper layers of the skin, there's a risk of permanent scars after the sores heal.

Immune System Complications

In some cases, impetigo can trigger an immune response that leads to complications involving other body systems. These immune-related complications may include:

• Post-Streptococcal Glomerulonephritis: This kidney condition can follow impetigo caused by certain strains of streptococcus bacteria. It results from the immune system's response to the infection and can lead to symptoms such as proteinuria (protein in the urine) and hematuria (blood in the urine).
• Rheumatic Fever: Though rare, this serious complication can also arise after streptococcal impetigo, affecting the heart, joints, nervous system, and skin.

Infection Spread

The bacteria causing impetigo can sometimes become resistant to common antibiotics, making treatment more challenging. One example is MRSA (Methicillin-Resistant Staphylococcus Aureus).

In cases where MRSA causes impetigo, the infection can be particularly difficult to treat due to resistance to common antibiotics.

Preventing these complications involves early detection and treatment of the offending bacteria, proper hygiene practices to prevent its spread, and careful monitoring of symptoms that could indicate a worsening condition.

Wrap Up

Impetigo is a highly contagious bacterial skin infection that requires proper understanding and management. Early detection, prompt antibiotic treatment, and adherence to prescribed medications are crucial for resolving the infection and preventing potential complications. Maintaining good hygiene practices, such as frequent handwashing, avoiding sharing personal items, and isolating infected individuals, can effectively control the spread of impetigo.

While usually not severe, impetigo can progress to more serious conditions if left untreated. Seeking timely medical attention and following preventive measures are essential for safeguarding individual and public health, especially in settings where close contact is common, such as schools and daycares.

By raising awareness and promoting effective strategies, the burden of impetigo can be reduced, ensuring better health outcomes for those affected.

Frequently Asked Questions

Can adults get impetigo?

Yes, although impetigo is more common among children, especially those involved in high-contact sports, adults can also contract the condition. It is often spread from children to adults within the same household due to its contagious nature.

Do you need antibiotics to heal impetigo?

Yes, treating impetigo with antibiotics can significantly speed up the healing process and prevent the infection from spreading. Without treatment, impetigo might spread to others or other body parts. Depending on the severity, a doctor may prescribe topical or oral antibiotics.

How long will it take for impetigo to go away?

You might see improvement within 72 hours with antibiotic treatment, and the course usually lasts 7 to 10 days. Without treatment, impetigo could resolve within a few weeks on its own​

At what point should you call a doctor if you suspect impetigo?

You should consult a doctor if you recognize symptoms of impetigo, if the condition worsens or doesn't improve with treatment, or if it recurs frequently.

How long does it take for a rash from impetigo to appear after bacteria exposure?

A rash from impetigo typically appears 4 to 10 days after exposure to the bacteria​.