Introduction

Impetigo is a common infection of the superficial layers of the skin, called epidermis. It’s a highly infectious bacterial skin infection that usually affects children between the ages of two to five. However, it can also occur in younger or older kids and even in adults,¹ especially those assigned male at birth.² It was predicted that in 2010, there would be approximately 140 million cases of impetigo worldwide.¹ The highest incidence occurs during summer and autumn.²

In this article, we will discuss the risks and causes of impetigo in adults, symptoms and diagnosis, and the available options for treatment. 

Risks and causes of impetigo in adults

Common risk factors

There are multiple risk factors that are responsible for the infection, they include:⁴

• Close contact with the infected individual: Perhaps, it could be your child or someone, you are taking care of, who has the infection
• Crowded living environment: Impetigo can spread by frequent skin-to-skin contact in crowded settings including childcare centres, schools, colleges and military barracks
• Hot and humid weather: When it comes to bacteria, impetigo is one of the infections that is more likely to spread in hot, humid climates which enhances the rapid development of bacteria
• Poor Hygiene: Practising unhealthy hygiene like irregular hand washing, bad skin care, and sharing personal items can be a predisposing factor
• Skin damage: This may occur due to minor traumas such as cuts, scratches, insect bites, or previous skin lesions. Also, it can occur due to skin diseases such as dermatitis,³ or in contact sports
• Weakened immune system: Conditions that weaken the immune system, such as obesity, diabetes, HIV, or AIDS, taking corticosteroids, and receiving chemotherapy can make adults more vulnerable to impetigo
• Low socio-economic level: It is found that low-income people have more susceptibility to acquire the infection, because of the lack of health education

Bacterial causes

Impetigo is caused by Staphylococcus aureus or Streptococcus pyogenes, and it is classified into two main categories:⁵

Non-bullous Impetigo (70% of cases)

It is also called Impetigo contagiosa, and it is caused by bacteria, either Staphylococcus aureus or Streptococcus pyogenes.

Features:

• Superficial honey-coloured crusted lesions
• Usually observed typically on the face (especially around the nose and mouth), and limbs (arms and legs)
• Can spread to surrounding areas through self-infection
• Transmitted to close contacts

Bullous Impetigo (30% of impetigo cases):

It is caused by toxin-producing S. aureus.

Features:

• Starts by rapidly enlarging, flaccid bullae (fluid-filled blisters)
• Bullae can burst and leak, leaving behind characteristics of an erythematous base (redness on skin due to inflammation) with an outer boundary of scale
• Commonly affects the trunk, extremities, and moist intertriginous regions (e.g., axillae, neck fold, diaper area)

However, there is another form of impetigo in the case of untreated cases that affects the deep tissue, it is known as Ecthyma. It affects deeper layers of the skin, causing large, painful blisters that break into sores. These sores crust over and may leave scars.

Mode of transmission

Impetigo can easily transmitted from person to person, as follows:

• Direct skin contact: It can be transmitted from sores or blisters of an infected one to a healthy one, especially if the person has damaged skin
• Touching the contaminated surface: If you touch a dirty surface and you don't wash your hands, then you have the chance to get the infection
• Sharing personal items: Sharing other things is not hygienic, like clothing and bed sheets

Symptoms and diagnosis of impetigo in adults

Distinguishing features in adults

Symptoms differ from one individual to another, and it includes the following:^6,7

• Fever: The patient may experience low-grade high temperature and fatigue
• Red Sores: The disease commonly starts with red sores that pop quickly, ooze for a few days, and then form a yellow-coloured crust. Impetigo sores are presented as a worsening painful and pruritic generalised rash.⁷ These are commonly found around the mouth and nose but can appear anywhere on the body, especially the trunk and limbs
• Blisters: In some cases, impetigo may cause larger fluid-filled blisters that can pop and leave raw, red skin. They are painful and itchy
• Itching and Irritation: The affected areas may feel warm or red, it is advisable to consult your general practitioner to prevent the situation from worsening. The skin may become itchy, this may spread the infection further as you scratch due to the infection
• Swollen Lymph Nodes: In more severe cases, the infection may cause swelling in the lymph nodes near the affected area, indicating that the body is fighting the infection

Diagnostic methods

The diagnosis of impetigo in adults relies on age and often on individual circumstances within the clinic. The process of diagnosis includes⁽⁸⁾:

History of the complaint: It is a key point and first step, the physician asks some questions, such as:

1. The symptoms.

2. The duration of the symptoms.

3. The distribution of the lesion.

4. Are there any risk factors? Like, recent skin trauma (cuts, insect bites, other skin conditions like eczema) or close contact with someone or family who has a known case of impetigo (skin issues).

5. Any chronic illness? Any immune disorder?

• Physical examination: The most important aspect of diagnosing is how the physician examines and evaluates the affected region
• Bacterial culture: This involves taking a swab of fluid from a sore and sending it to a lab to identify the specific bacteria causing the infection

Differential diagnosis

Impetigo is a common disease that needs to be differentiated from other disease as follows⁽²⁾:

• Herpes simplex
• Scabies
• Varicella zoster (shingles)
• Contact dermatitis
• Candidiasis (Thrush)
• Atopic dermatitis

Complications of Impetigo

There are many complications associated with impetigo, which include:⁹

• Cellulitis (Nonbullous Form): Infection spreads to deeper layers of skin
• Septicemia: Bacteria enter the bloodstream, causing a systemic infection
• Osteomyelitis: Infection reaches the bone
• Septic Arthritis: Joint infection
• Lymphangitis: Inflammation of lymphatic vessels
• Lymphadenitis: Infection of lymph nodes
• Guttate Psoriasis: Skin condition triggered by streptococcal infection
• Staphylococcal Scalded Skin Syndrome: Serious skin condition caused by S. aureus toxins
• Acute Poststreptococcal Glomerulonephritis (APSGN): Most serious complication, affecting the kidneys

Treatment options for adult impetigo

While untreated impetigo is often self-limited, treatment is important for symptom control, limiting the spread of infection and causing complications, it includes:

Topical antibiotic ointments

 It is applied only on the needed lesion, usually prescribed for a seven-day course. However, there are potential side effects, as follows:⁹

• Local allergic reactions
• Skin sensitisation
• Difficulty applying to certain areas (e.g., eyelids, mouth, back)

The preparation

• Mupirocin 2% cream or ointment (Bactroban)
• Retapamulin 1% ointment (Altabax)
• Fusidic acid

Oral antibiotic medications

They are used for impetigo with large sized bullae or when no response with topical therapy. Treatment duration (usually seven days) can be extended if needed.

The preparation 

• Amoxicillin/clavulanate (Augmentin)
• Cephalexin
• Clindamycin
• Dicloxacillin
• Doxycycline
• Trimethoprim-sulfamethoxazole

Caring for impetigo in adults

Hygiene and cleaning of affected areas

In order to help heal and stop the impetigo from spreading, it is necessary to keep the affected areas properly clean and try to avoid scratching them.

Infected area cleaning

• Wash the area around the infection with mild soap and water
• Remove the crusts with care to let the topical antibiotic work on the skin

Prevention of spreading to others

Spread prevention

• Keep the infected area covered with a clean and dry dressing
• Avoid touching or scratching the skin area with sores
• Wash hands frequently, especially if they are dirty, and after touching the infected area

 How to avoid transmitting the disease?⁽⁶⁾

•  It is essential not to share personal stuff such as towels (face and hand), bed sheets, clothing, etc.

• If you have impetigo, keep your stuff separate and clean them thoroughly.

Preventative methods

To reduce your chances of having another case of impetigo:

• Always maintain good personal hygiene
• Take care of minor cuts and abrasions promptly
• Keeping your nails short and clean will cut down the chance of spreading the bacteria by scratching.

FAQ`s

When to call for medical advice?

You need to seek a medical attention, when:

• There is no improvement after a few days of treatment
• The infection is spreading or getting worse
• Signs of systemic infection (e.g., fever, chills) develop

How long is impetigo contagious?

Usually,without treatment, impetigo can be contagious for weeks. After starting impetigo treatment, the condition is contagious until:

• The rash disappears
• Scabs fall off
• You’ve finished at least two days of antibiotics

How long does it take to get impetigo after being exposed?

It takes around 4-10 days to show off the symptoms.

Can you go near someone with impetigo?

It is not advisable to come in contact with someone infected with impetigo.

Summary

Impetigo is a common skin disease caused by bacteria. It spreads more among children, but it can affect adults. The prevention method is a cornerstone to protect others from getting impetigo.