Impetigo: A Common Bacterial Skin Infection

Impetigo: A Common Bacterial Skin Infection

What is Impetigo?

Impetigo is an acute, contagious bacterial skin infection caused by Streptococcus and Staphylococcus aureus bacteria. It usually affects the superficial layers of the skin and is most common in children.

Triggering Factors:

Impetigo often occurs after skin trauma, such as scratches, open wounds, insect bites, chickenpox or blistering skin diseases.

Predisposing Factors:

• Hot and humid weather

• Poor hygiene

• Pre-existing skin diseases

• Weakened immunity: HIV, organ transplantation, diabetes, chemotherapy, radiation therapy, corticosteroid use.

Classification:

Impetigo is divided into two main groups:

• Non-bullous impetigo: Lesions are typically small blisters that quickly become pustular, with a diameter of less than 2 cm. Pustules easily rupture, leaving honey-colored crusts on a moist red base.

• Common locations: Around natural openings like the nose, mouth, and limbs. Lesions tend to spread and coalesce into larger plaques.

• Bullous impetigo: Lesions are shallow, thin-walled blisters, larger than 3 cm, containing clear yellow fluid.

• When ruptured, blisters leave a ring of crusts surrounding a moist red area, without crusts, later turning brown or skin-colored.

• Common locations: Face, limbs, trunk, armpits, perianal area in infants.

• Bullous impetigo is less contagious than non-bullous impetigo and usually involves only a few lesions.

Symptoms:

• Severe cases may experience fever, swollen lymph nodes, diarrhea, fatigue, and poor appetite.

• Impetigo can develop on skin already affected by blisters, such as chickenpox, pemphigus, pemphigoid.

Course:

• Self-resolves in 2-3 weeks without treatment.

• Resolves in 7-10 days with appropriate treatment.

• If left untreated, it can lead to complications such as cellulitis, vasculitis, lymphadenitis, bacteremia, staphylococcal pneumonia.

Diagnosis:

• Cytology: Blisters show acantholysis, numerous neutrophils.

• Bacteriology: Gram staining identifies bacteria, bacterial cultures for identification.

• Bacteriology is mainly for treatment guidance rather than definitive diagnosis.

Differential Diagnosis:

• Chickenpox

• Staphylococcal scalded skin syndrome

• Scabies

• Herpes infection

• Autoimmune blistering diseases

Treatment:

• Local care:

• Cleanse with normal saline solution.

• Remove crusts with moist gauze and Jarish solution.

• Use antibacterial soaps or solutions.

• Topical antibiotics:

• Mupirocin

• Fucidic acid

• Retapamulin

• Mupirocin is preferred due to lower bacterial resistance.

• Fucidic acid is less used due to high resistance.

• Systemic antibiotics:

• Bullous impetigo

• Disseminated non-bullous impetigo

• Impetigo affecting the whole body

• Beta-lactam group:

• Amoxicillin: 50 mg/kg/day divided 3 times

• Clixacilim: 50-100 mg/kg/day divided 4 times, maximum 4g

• Oxacillin: 12.5-25 mg/kg every 6 hours

• Methicillin-resistant Staphylococcus aureus (MRSA) impetigo:

• Trimethoprim/ sulfamethoxazole

• Doxycycline: Children over 8 years old.

Note: This article is for informational purposes only and does not replace medical advice from a healthcare professional. Please consult with a doctor for proper diagnosis and treatment.