Highly contagious and common bacterial infection of the skin that typically occurs in children; a key consideration for schools and playgroups.
Typically staphylococcal or streptococcal. Diagnosis is usually clinical; bacterial skin cultures are reserved for extensive disease or where there is risk of spread of infection.
Skin that has been broken by minor trauma or other disease is particularly susceptible to infection.
Tends to resolve spontaneously or with topical antiseptics.
Topical antibiotics are effective, but resistance may be an issue in some regions.
Systemic antibiotics may be necessary; for example, if infection is recalcitrant to topical treatment, if there is concern about complications (e.g., acute rheumatic fever), or if deeper infection is suspected.
Impetigo is a superficial, contagious, blistering infection of the skin caused by the bacteria Staphylococcus aureus and Streptococcus pyogenes. It has two forms: nonbullous and bullous. Bullae are fluid-filled lesions >0.5 cm in diameter.
Nonbullous impetigo is the more common form (70% of cases). Though bullae are not present in this form, vesicles (fluid-filled lesions <0.5 cm in diameter) may appear transiently early in the disease. Etiologic agents are Staphylococcus aureus, Streptococcus pyogenes, or a combination of the 2 organisms. Lesions occur at sites of skin trauma.
Bullous impetigo is due to Staphylococcus aureus skin infection. Lesions occur on intact skin.
History and exam
Key diagnostic factors
Other diagnostic factors
- mucopurulent exudate
- increased humidity
- poor hygiene, malnutrition, and overcrowding
- chronic colonization with Staphylococcus aureus - nasal, axillary, pharyngeal, perineal
- concomitant skin disease
1st investigations to order
- clinical diagnosis
Investigations to consider
- bacterial skin culture
neonates: nonbullous impetigo
neonates: bullous impetigo
adults, children, and infants: superficial or limited infection
adults, children, and infants: widespread cutaneous lesions
adults, children, and infants: deep soft tissue infection or hematogenous spread
- Herpes simplex
- Dermatophytosis (Tinea corporis, Tinea capitis)
- Cellulitis and other bacterial skin infections
- Practice guidelines for the diagnosis and management of skin and soft tissue infections
ImpetigoMore Patient leaflets
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