Impetigo

Impetigo is a common and highly contagious bacterial infection that primarily affects the surface layers of the skin. It is most frequently seen in infants and young children but can occur at any age. This comprehensive guide will talk about the intricacies of impetigo, exploring its causes, various types, characteristic symptoms, diagnostic methods, and the range of effective treatment options available. 

Impetigo is a superficial bacterial infection of the skin. The infection occurs in the epidermis, the outermost layer of the skin. The bacteria responsible for impetigo, most commonly Staphylococcus aureus (often referred to as staph) and Streptococcus pyogenes (often referred to as strep), can enter the skin through small cuts, insect bites, or other breaks in the skin barrier. In some cases, impetigo can also develop on healthy skin.

The hallmark of impetigo is the development of characteristic skin lesions. These typically begin as small, red spots that quickly develop into thin-walled blisters (vesicles or bullae). These blisters are fragile and rupture easily, releasing a yellowish or honey-coloured fluid that dries to form a distinctive golden-brown crust. The affected areas can be itchy, but generally, impetigo is not painful.

Impetigo is highly contagious and can spread easily through direct contact with the sores or with items that have been in contact with the sores, such as towels, clothing, and toys. This is why it is crucial for individuals with impetigo and their close contacts to take precautions to prevent its transmission.

Impetigo is a common skin infection worldwide, particularly in warm, humid climates and in settings where close contact is common, such as schools and daycare centres.

Worldwide Prevalence: Globally, the prevalence of impetigo varies depending on geographical location, socioeconomic conditions, and hygiene practices. It is significantly more common in developing countries and in areas with overcrowding and poor sanitation.

Prevalence in India: In India, impetigo is a significant public health concern, particularly in rural and underserved communities where access to hygiene facilities and healthcare may be limited. The exact figures can vary depending on the region and study population, but impetigo is consistently reported as a common cause of skin infections in paediatric populations.

There are two main types of impetigo:

Non-bullous Impetigo (Crusted Impetigo)

This is the most common form of impetigo, accounting for approximately 70% of cases. It typically begins as small, red papules that quickly develop into vesicles or pustules. These lesions rupture easily, releasing a honey-coloured fluid that dries to form a characteristic golden-brown, stuck-on crust. The sores often start around the nose and mouth but can spread to other areas of the body through scratching or direct contact. There may be small, satellite lesions surrounding the primary sores. Itching is common with this type of impetigo.
 

Bullous Impetigo

This form is less common and is almost always caused by Staphylococcus aureus bacteria that produce a toxin that causes the formation of larger, fluid-filled blisters (bullae). These bullae are often clear or yellowish and may be several centimetres in diameter. They typically appear on the trunk, arms, and legs. The bullae rupture more slowly than the vesicles in non-bullous impetigo, and when they do, they leave behind a thin, varnish-like crust rather than the thick, honey-coloured crust seen in the non-bullous form. Itching is usually less prominent with bullous impetigo.
 

A less common and more serious form of streptococcal skin infection that is sometimes considered a deeper form of impetigo is ecthyma. Ecthyma involves deeper layers of the skin (the dermis) and presents as punched-out ulcers with a thick, crusted surface and raised, violaceous borders. Ecthyma is more likely to cause scarring and can be associated with systemic symptoms.

Impetigo is caused by bacterial infection, primarily with one of two types of bacteria:

• Staphylococcus aureus (Staph): This is the most common cause of impetigo, including both the non-bullous and bullous forms. Some strains of Staphylococcus aureus produce toxins that lead to the formation of the larger blisters seen in bullous impetigo.
• Streptococcus pyogenes (Strep): This bacterium is also a common cause of non-bullous impetigo. In some cases, impetigo can be caused by a co-infection with both staph and strep bacteria.

These bacteria can enter the skin in several ways:

• Through Breaks in the Skin: Even minor cuts, scrapes, insect bites, eczema, or other skin conditions that disrupt the skin barrier can provide an entry point for the bacteria.
• Direct Contact: The bacteria can be spread through direct skin-to-skin contact with someone who has impetigo.
• Contact with Contaminated Objects: Touching objects or surfaces that have been contaminated with the bacteria, such as towels, bedding, toys, and clothing, can also lead to infection.

Impetigo can occur on otherwise healthy skin, known as primary impetigo. It can also occur as a secondary infection, developing on skin that is already affected by another condition, such as eczema, chickenpox, or scabies. In these cases, the underlying skin condition provides the initial break in the skin that allows the bacteria to enter and cause infection.

Factors that can increase the risk of impetigo include warm, humid weather, poor hygiene, overcrowding, and participation in contact sports. Once the bacteria colonise the skin, they multiply and cause the characteristic inflammation and lesions of impetigo.

The symptoms of impetigo vary slightly depending on the type:

Non-bullous Impetigo

• Small, red spots (papules): These are the initial lesions.
• Small blisters or pustules (vesicles or pustules): These develop quickly from the red spots.
• Oozing fluid: The blisters rupture easily, releasing a yellowish or honey-coloured fluid.
• Honey-coloured crusts: The fluid dries to form a characteristic golden-brown, stuck-on crust over the sores.
• Itching: The affected areas are often itchy.
• Spread of lesions: The sores can spread to other parts of the body through scratching and touching.
• Small, satellite lesions: New, smaller sores may appear around the original lesions.
• Most common locations: Around the nose and mouth, but can occur on other areas of the face, arms, legs, and trunk.

Bullous Impetigo

• Larger blisters (bullae): These are fluid-filled and can be clear or yellowish.
• Thin, varnish-like crust: When the bullae rupture, they leave behind a thin, translucent or yellowish crust.
• Less itching: Itching may be less prominent compared to non-bullous impetigo.
• Most common locations: Trunk, arms, and legs.

Ecthyma

• Deeper ulcers: Punched-out sores that extend into the deeper layers of the skin.
• Thick, crusted surface: The ulcers are covered with a thick crust.
• Raised, violaceous borders: The edges of the ulcers may be raised and purplish.
• Pain or tenderness: The lesions may be painful or tender.
• Scarring: Ecthyma is more likely to cause scarring.
• Possible systemic symptoms: In some cases, there may be associated swollen lymph nodes or fever.

Diagnosis of impetigo is usually based on a clinical examination of the characteristic skin lesions. A doctor will typically be able to identify impetigo by its appearance, particularly the honey-coloured crusts in non-bullous impetigo or the larger blisters in bullous impetigo.

In most straightforward cases, no laboratory tests are needed for diagnosis. However, in certain situations, the doctor may decide to take a swab of the infected skin for bacterial culture. This may be done to:

• Confirm the diagnosis: If the presentation is atypical or if there is concern about antibiotic resistance.
• Identify the specific bacteria: Knowing whether the infection is caused by staph or strep can sometimes influence treatment choices, especially if there are recurrent infections.
• Rule out other conditions: If there is uncertainty about the diagnosis, a culture can help to differentiate impetigo from other skin infections.

Blood tests are not typically used to diagnose uncomplicated impetigo. However, if there are concerns about deeper infections or systemic involvement (which is rare with typical impetigo), blood tests might be ordered.

The doctor will also take a history of the illness, including the onset of symptoms, any preceding skin injuries or conditions, and any known exposure to others with impetigo.

The treatment for impetigo depends on the extent and severity of the infection:

Topical Antibiotics

For mild, localised impetigo, topical antibiotic ointments or creams are usually sufficient. Common topical antibiotics used include mupirocin (Brand available: T-Bact) and retapamulin. The crusts should be gently soaked and removed before applying the topical antibiotic as directed by the doctor, typically two to three times a day for 5-7 days. It's crucial to complete the entire course of antibiotics, even if the skin appears to be healing.
 

Oral Antibiotics

For more widespread or severe impetigo, or if topical treatment is not effective, oral antibiotics are usually prescribed. The choice of oral antibiotic will depend on the likely causative bacteria and local antibiotic resistance patterns. Common oral antibiotics used include cephalexin, amoxicillin-clavulanate, clindamycin, and trimethoprim-sulfamethoxazole.

The duration of oral antibiotic treatment is typically 5-10 days. It is essential to complete the entire course of oral antibiotics as prescribed to ensure the infection is fully eradicated and to prevent the development of antibiotic resistance.
 

General Measures

In addition to antibiotic treatment, several general measures are important in managing impetigo and preventing its spread:

• Gentle Washing: The affected areas should be washed gently with soap and water.
• Soaking and Crust Removal: Soaking crusted areas with warm, soapy water can help to soften and remove the crusts, allowing the topical antibiotic to penetrate better.
• Avoid Touching and Scratching: It's important to avoid touching the sores to prevent spreading the infection to other parts of the body or to other people. Scratching should be avoided as it can worsen the infection and increase the risk of scarring.
• Hand Hygiene: Frequent and thorough hand washing with soap and water is crucial for preventing the spread of impetigo.
• Avoid Sharing Personal Items: Towels, washcloths, clothing, and razors should not be shared with others.
• Covering Sores: Loose bandages can help to protect the sores and reduce the risk of spread, especially in young children who may have difficulty avoiding touching them.

Follow-up with the doctor may be necessary to ensure the infection is clearing up appropriately. If the impetigo does not improve with treatment or if new sores develop, further evaluation and a change in antibiotics may be required.

Several factors can increase the risk of developing impetigo:

• Age: Impetigo is most common in children between the ages of 2 and 5 years.
• Close Contact: Living in crowded conditions, attending daycare centres or schools, and participating in contact sports increase the risk of transmission.
• Poor Hygiene: Inadequate hygiene practices can contribute to the spread of bacteria.
• Warm, Humid Weather: Impetigo is more prevalent in warm, humid climates.
• Breaks in the Skin: Cuts, scrapes, insect bites, and underlying skin conditions like eczema, chickenpox, and scabies provide entry points for bacteria.
• Weakened Immune System: Individuals with compromised immune systems may be more susceptible to skin infections.
• Contact with Infected Individuals: Direct contact with someone who has impetigo is a significant risk factor.

Impetigo is usually a mild condition that resolves with appropriate treatment. However, potential complications, although rare, can occur:

• Cellulitis: The infection can spread deeper into the skin and subcutaneous tissue, causing cellulitis, which is characterised by redness, warmth, swelling, and pain.
• Post-streptococcal Glomerulonephritis: In rare cases, impetigo caused by certain strains of Streptococcus pyogenes can lead to a kidney disorder called post-streptococcal glomerulonephritis. This typically occurs 1-3 weeks after the skin infection.
• Scarring: While uncommon with non-bullous impetigo, deeper infections like ecthyma are more likely to cause scarring.
• Staphylococcal Scalded Skin Syndrome (SSSS): This is a more serious condition caused by toxins produced by certain strains of Staphylococcus aureus. It is more common in young children and involves widespread blistering and peeling of the skin.
• Rheumatic Fever: This is a rare inflammatory condition that can occur after a Streptococcus pyogenes infection, but it is more commonly associated with strep throat than with impetigo.

If you or someone you know has impetigo, these tips can help manage the condition and prevent its spread:

• Follow Doctor's Instructions: Adhere strictly to the prescribed antibiotic treatment and application instructions.
• Maintain Good Hygiene: Practise frequent hand washing and avoid sharing personal items.
• Gently Clean Sores: Gently wash the affected areas with soap and water and carefully remove any loose crusts as advised by your doctor.
• Cover Sores: Keep sores covered with a loose bandage to protect them and reduce the risk of spread.
• Avoid Scratching: Try to avoid scratching the sores, as this can worsen the infection and spread it to other areas.
• Complete the Full Course of Antibiotics: Even if the sores start to look better, finish the entire course of antibiotics as prescribed by your doctor to ensure the infection is fully cleared.
• Isolate Infected Individuals: Follow guidelines regarding staying home from school or work to prevent further transmission.
• Inform Close Contacts: Alert family members, school officials, or daycare providers about the infection so they can take necessary precautions and monitor for symptoms.

"You don't need antibiotics for impetigo."

While mild, very localised cases might sometimes clear up on their own, antibiotic treatment is generally recommended to shorten the duration of the infection, reduce the risk of spread, and prevent complications.

“Once the crusts are gone, it's no longer contagious.” 

Impetigo remains contagious until the bacteria are eradicated with antibiotic treatment, even if the crusts have fallen off.

“Impetigo is a serious condition.”

While highly contagious and sometimes bothersome, impetigo is usually a mild skin infection that responds well to treatment. Serious complications are rare.

You should see a doctor if you or your child develops symptoms of impetigo, such as:

• Red sores that quickly turn into blisters.
• Oozing fluid from the blisters.
• Honey-coloured crusts on the skin.
• Spreading sores.
• Signs of a more severe infection, such as fever, swelling, or pain around the sores.
• Impetigo that does not improve with over-the-counter antiseptic treatments (which are generally not effective for impetigo).
• Recurrent episodes of impetigo.

When you see your doctor about impetigo, consider asking the following questions:

• What type of impetigo do I have?
• What is the best treatment for my impetigo?
• Do I need topical or oral antibiotics?
• How should I apply the medication?
• How long will the treatment last?
• When is it safe for me or my child to return to school or work?
• How can I prevent the spread of impetigo to others?
• Are there any specific hygiene measures I should follow?
• How can I prevent future infections?

Supporting someone with impetigo involves understanding the nature of the infection and taking appropriate precautions:

• Remind them to take their antibiotics as prescribed and apply topical medications correctly.
• Assist young children with frequent hand washing and avoiding touching their sores.
• Ensure they have their own towels, washcloths, and other personal items and that these are not shared.
• The sores can be itchy and uncomfortable. Offer gentle support and discourage scratching.
• Follow isolation guidelines to prevent the spread of the infection to others.

Impetigo is a common and highly contagious bacterial skin infection that primarily affects children. Characterised by distinctive sores that progress to blisters and honey-coloured crusts, it is usually caused by Staphylococcus aureus or Streptococcus pyogenes bacteria. While generally mild and treatable with topical or oral antibiotics, prompt diagnosis and adherence to treatment can prevent its spread and minimise the risk of complications.