Clinical Notes : Dermatology

211. Impetigo

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Impetigo

 

Impetigo is a common superficial bacterial infection of the skin that is most often seen in children :

  • the non-bullous form is most common in children aged 2–5 years

  • bullous impetigo is more common in children under 2 years of age.

 

Lesions can develop anywhere on the body but are most common on the face.

The two main clinical forms of impetigo are :

  • non-bullous impetigo accounts for around 70% of cases 

  • bullous impetigo

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Impetigo is usually caused by Staphylococcus aureus, Streptococcus pyogenes or a combination of both.

Lesions begin as thin-walled vesicles or pustules, which release exudate forming a characteristic golden crust.

Bullous impetigo is caused by toxin production, causing loss of cell adhesion in the superficial skin surface resulting in fluid filled lesions.

 

Impetigo caused by methicillin-resistant Staphylococcus aureus (MRSA) is becoming increasingly common.

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Impetigo is a self-limiting, non-scarring condition, which usually resolves in 2–3 weeks without treatment.

 

Complications are uncommon; however, untreated individuals remain infectious.

 

In order to prevent outbreaks, children should be excluded from school or other childcare institutions until lesions are crusted and healed, or for 48 hours after commencing treatment.

 

Good hygiene measures (e.g. washing hands regularly and using separate towels) help prevent spread of impetigo to other areas of the body and to other people.

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Primary Care Treatment of Impetigo

Advice to reduce the spread of impetigo

 

Advise people with impetigo, and their parents or carers if appropriate, about good hygiene measures to reduce the spread of impetigo to other areas of the body and to other people.

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Initial Treatment

 

Localised non-bullous impetigo

 

  • Consider hydrogen peroxide 1% cream for people with localised non-bullous impetigo who are not systemically unwell or at high risk of complications.

  • Although other topical antiseptics are available for treating superficial skin infections, no evidence was found for using them to treat impetigo

 

  • If hydrogen peroxide 1% cream is unsuitable, offer a short course of a topical antibiotic for people with localised non-bullous impetigo who are not systemically unwell or at high risk of complications

 

 

Widespread non-bullous impetigo

  • Offer a short course of a topical or oral antibiotic for people with widespread non-bullous impetigo who are not systemically unwell or at high risk of complications.

  • Take into account:

    • that topical and oral antibiotics are both effective at treating impetigo

    • the preferences of the person and, if appropriate, their parents or carers, including the practicalities of administration (particularly to large areas) and possible adverse effects

    • previous use of topical antibiotics, because antimicrobial resistance can develop rapidly with extended or repeated use

 

 

Bullous impetigo or impetigo in people who are systemically unwell or at high risk of complications

  • Offer a short course of an oral antibiotic for:

    • all people with bullous impetigo

    • people with non-bullous impetigo who are systemically unwell or at high risk of complications

 

 

Combination treatment

  • Do not offer combination treatment with a topical and oral antibiotic to treat impetigo

 
 
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Reassessment and further treatment

  • Reassess people with impetigo if their symptoms worsen rapidly or significantly at any time or have not improved after completing a course of treatment

  • When reassessing people with impetigo, take account of:

    • other possible diagnoses, such as herpes simplex

    • any symptoms or signs suggesting a more serious illness or condition, such as cellulitis

    • previous antibiotic use, which may have led to resistant bacteria

 

  • For people with impetigo that is worsening or has not improved after treatment with hydrogen peroxide 1% cream, offer:

    • a short course of a topical antibiotic if the impetigo remains localised or

    • a short course of a topical or oral antibiotic if the impetigo has become widespread (see the recommendation on widespread non-bullous impetigo)

 

  • For people with impetigo that is worsening or has not improved after completing a course of topical antibiotics:

    • offer a short course of an oral antibiotic (see the recommendations on choice of antimicrobial) and

    • consider sending a skin swab for microbiological testing

 

  • For people with impetigo that is worsening or has not improved after completing a course of oral antibiotics, consider sending a skin swab for microbiological testing

 

  • For people with impetigo that recurs frequently:

    • send a skin swab for microbiological testing and

    • consider taking a nasal swab and starting treatment for decolonisation

 

  • If a skin swab has been sent for microbiological testing:

    • review the choice of antibiotic when results are available and

    • change the antibiotic according to results if symptoms are not improving, using a narrow-spectrum antibiotic if possible.

 

Referral and seeking specialist advice

  • Refer to hospital:

    • people with impetigo and any symptoms or signs suggesting a more serious illness or condition (for example, cellulitis)

    • people with widespread impetigo who are immunocompromised

 

  • Consider referral or seeking specialist advice for people with impetigo if they:

    • have bullous impetigo, particularly in babies (aged 1 year and under)

    • have impetigo that recurs frequently

    • are systemically unwell

    • are at high risk of complications

 

Necrotising Fasciitis

 

In any patient presenting with skin infection, it is vital to exclude necrotising fasciitis, a rare but destructive and rapidly progressive infection that involves deep tissues, fascia, and muscles.

 

Necrotising fasciitis has a significant mortality rate and may require extensive surgical debridement.

 

The presenting signs are often non-specific (redness, swelling, and pyrexia); however, patients may be systemically unwell.

The key symptom is pain disproportionate to the clinical signs.

 

Immediate surgical referral and admission to hospital is vital if the condition is suspected.

 
 
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Impetigo: antimicrobial prescribing.

NICE Guideline 153.

NICE, 2020

Access

Impetigo

DermNetNZ

accesses March 2021

Access

Impetigo

Primary Care Dermatology Society.

accessed March 2021

Access

Infective skin conditions : when is it appropriate to prescribe an antibiotic ?

Dr. Caroline Ward

Guidelines in Practice

June 2020

Access

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Hydrogen peroxide 1% cream is available in Ireland as Crystacide (Cream, Lipid stabilised Hydrogen Peroxide 1% w/w)

Fucidic acid 2% is available in Ireland as Fucidin.

Mupirocin 2% is available in Ireland as Bactroban.

 

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