Impetigo

Introduction

Impetigo is a highly contagious superficial bacterial infection of the skin affecting the stratum corneum of the epidermis. It is particularly common among children, crowded households, and populations living in disadvantaged or resource-limited settings.

Transmission occurs through:

• Direct skin-to-skin contact

• Contact with contaminated objects (towels, clothes, bedding)

• Self-inoculation from scratching

Small family, daycare, or school outbreaks are frequent.

Important clinical note:Impetigo is mainly a clinical diagnosis. In children, lesions typically occur around natural body openings (orifices), especially around the mouth and nose.

Etiology (Causative organisms)

Most commonly caused by:

• Staphylococcus aureus

• Streptococcus pyogenes (Group A Streptococcus)

Types:

1. Non-bullous impetigo – most common (≈70%)

2. Bullous impetigo – toxin-producing staphylococci

Risk Factors

• Poor hygiene

• Crowding

• Malnutrition

• Warm humid climate

• Minor skin trauma (scratches, insect bites, scabies, eczema)

• Nasal carriage of Staphylococcus aureus

• Immunocompromised states

Signs & Symptoms

Typical skin findings:

• Polycyclic vesicles or blisters containing pus

• Fragile vesicles that rupture easily

• Early lesions isolated or confluent erosions

• Characteristic yellowish “honey-colored” crusts

• Mild itching (common)

• Usually painless

Severe cases may show:

• Fever (pyrexia)

• Lymph node enlargement

• Malaise

Diagnostic Criteria

Diagnosis is clinical when the following are present:

• Polycyclic vesicles or pustules

• Superficial erosions

• Honey-colored crusts

• Typical distribution around mouth/nose in children

Investigations

Not required in typical cases.

Consider tests only when:

• Recurrent infections

• Treatment failure

• Suspected MRSA

• Outbreak investigation

Possible tests:

• Bacterial swab culture & sensitivity

• Blood glucose (recurrent infections)

• HIV testing in persistent cases

Management

Non-Pharmacological Treatment

• Improve personal hygiene

• Frequent hand washing

• Wash lesions gently with soap and clean water

• Remove crusts before applying medication

• Keep nails short

• Avoid sharing towels, clothes, bedding

• Isolate affected children from school/daycare for 24 hrs after starting antibiotics

Pharmacological Treatment

Topical therapy (first-line for localized disease)

1. Potassium permanganate (PP) wet dressing

   • 1:40,000 (0.025%) solution

   • Apply every 12 hours

   • Duration: 3–4 days

   • Each session: 15–20 minutes

2. Gentian Violet (G.V) paint 0.5%

   • Every 12 hours

   • For 5 days

3. Mupirocin 2% ointment

   • Every 12 hours

   • 5–7 days

OR

4. Fusidic acid cream

   • Every 12 hours

   • 5–7 days

Systemic Antibiotics

Indicated when:

• Extensive lesions

• Fever/systemic symptoms

• Lymphadenopathy

• Recurrent infection

• Failure of topical therapy

• Outbreak control

Options:

Phenoxymethylpenicillin

• Adults: 500 mg PO every 6 hours for 7 days

• Children: 25 mg/kg every 6 hours

OR

Erythromycin

• Adults: 500 mg PO every 6 hours for 10 days

• Children: 25–50 mg/kg every 8 hours

OR

Amoxicillin + Clavulanic acid

• 625 mg PO every 8 hours for 5 days

Complications

Although usually mild, untreated impetigo may cause:

• Cellulitis

• Abscess formation

• Lymphangitis

• Acute post-streptococcal glomerulonephritis

• Rarely rheumatic fever

Prevention

• Early treatment of infected individuals

• Daily bathing with soap

• Hand hygiene education

• Avoid scratching insect bites and scabies lesions

• Treat underlying skin diseases (eczema, scabies)

• Clean shared items (towels, toys, bedding)

• Exclude infected children from school until 24 hrs after treatment starts

• Screen and treat nasal carriers in recurrent family outbreaks