Impetigo

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Impetigo\: common super
Forms\: non-bullous (most common, honey-coloured crusted lesions) and bullous (blisters or bullae).
Aetiology\:
Non-bullous\: bacteria enter through minor trauma.
Bullous\: staphylococcus bacteria invade intact skin.
Risk factors\: pre-existing skin damage (e.g., eczema), skin trauma.
Clinical features\:
S t r e p t o c o c c u s p y o g e n e s .
Non-bullous\:
Bullous\:
Di
epidermal necrolysis.
Investigations\: usually clinical diagnosis; swabs for culture if extensive area, non-responsive to treatment, or MRSA
suspected.
Management\:
Conservative\: hygiene advice, avoid school/work until lesions are dry/crusted or after 48 hours of antibiotics.
Medical\:
Non-bullous\: hydrogen peroxide 1% cream (localised), topical antibiotics (fusidic acid 2% or mupirocin 2%), oral antibiotics
(
Bullous\: oral antibiotics (
Complications\:
Superadded infection leading to cellulitis/sepsis.
Scarlet fever or glomerulonephritis if caused by Group A β-haemolytic streptococcus.
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Introduction

Impetigo is a common super
or S t r e p t o c o c c u s p y o g e n e s .
¹
It most often a
1.6% in children who are 5-15 years old.
²
Impetigo can present in the non-bullous or bullous form. Non-bullous impetigo is the most common and recognisable
form and presents as the typical, crusted honey-coloured lesions.Aetiology
Non-bullous impetigo
Non-bullous impetigo is usually caused by bacteria (S t a p h y l o c o c c u s a u r e u s or S t r e p t o c o c c u s p y o g e n e s ) entering the skin
through a site of minor trauma.
¹
Bullous impetigo
Bullous impetigo is similar to non-bullous impetigo but is usually caused by staphylococcus bacteria which invade intact
skin and damage the super
¹

Risk factors

Any pre-existing damage to the skin barrier (such as atopic eczema) or trauma to the skin can predispose an individual to
developing impetigo.

Clinical features

Non-bullous impetigo
Small
characteristic honey-coloured crusted lesions.
These commonly appear on the hands or face, particularly around the mouth or chin area.
Figure 1. Non-bullous impetigo
Bullous impetigo
Similarly to non-bullous impetigo, bullous impetigo begins with small
into large
It is more likely to occur in areas of pre-existing eczematous skin but can occur anywhere on the body. Bullous impetigo
can be painful, and patients can feel generally unwell.
Bullous impetigo tends to commonly a
²
Figure 2. Bullous impetigo

Di

Di
Herpes simplex virus\: this can present similarly with small crops of vesicles, which erode and are typically painful in
nature. These can present around the mouth (type 1) or the genitalia following sexual contact (type 2).Chickenpox\: caused by the varicella-zoster virus; this most commonly presents in children with general malaise and
fever accompanied by crops of vesicles which progress to become pustular before crusting over.
Cellulitis\: often presents with a demarcated area of erythema, swelling and warmth. There are usually no vesicles or
pustules present.
Bullous pemphigoid\: this most commonly presents in the elderly with tense, large blisters on the limbs or trunk.
Steven-Johnson syndrome / toxic epidermal necrolysis\: patients may have a
forms, this typically spreads within hours; the a

Investigations

Impetigo is usually a clinical diagnosis based on examination
However, swabs of the a
An extensive area of skin is a
The lesions do not respond to treatment
Methicillin-resistant Staphylococcus aureus (MRSA) infection is suspected

Management

Conservative management
Conservative management for all patients with impetigo includes\:
Hygiene advice such as regular hand washing, avoiding touching the a
people.
Advice not to attend school or work until the lesions are dry and crusted over, or have had 48 hours of oral antibiotics.
Medical management
Patients with impetigo should be referred urgently to secondary care if they are presenting with complications of impetigo
or are immunocompromised and have widespread impetigo.
Non-bullous impetigo
If localised, o
used such as fusidic acid 2% or mupirocin 2%.
Oral antibiotics such as
Bullous impetigo
further assessment.
O

Complications

Complications of impetigo include\:
Superadded infection of the impetiginous lesions can lead to cellulitis and even sepsis. It is important to assess the
patient thoroughly and record basic observations (vital signs).
In the rare event that impetigo is caused by Group A β-haemolytic streptococcus, this can lead to the development of
scarlet fever or glomerulonephritis.
Any patient presenting with complications associated with impetigo requires urgent referral to secondary care.

References

DermNet NZ. I m p e t i g o . Last updated 2022.Available from\: [LINK]NICE CKS. I m p e t i g o . Last updated 2020. Available from\: [LINK]
Image references
Figure 1 James Heilman, MD. I m p e t i g o 2 0 2 0 . Licence\: [CC BY-SA]
Figure 2 Littlekidsdoc. B u l l o u s i m p e t i g o 1 . Licence\: [CC BY-SA]

Reviewer

Dr Thomas King
Consultant Dermatologist

Related notes

Acne vulgaris
Basal Cell Carcinoma (BCC)
Cellulitis
Cutaneous Squamous Cell Carcinoma (SCC)
Erythema Multiforme

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Contents

Introduction
Aetiology
Risk factors
Clinical features
Di
Investigations
Source\: geekymedics.com