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: non-bullous and bullous. Bullae are fluid-filled lesions of >0.5 cm in diameter.
Non-bullous 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. Aetiological agents are Staphylococcus aureus, Streptococcus pyogenes, or a combination of the two 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
Michael Freeman, MB BS, FACD, FRACGP
MF declares that he has no competing interests.
Dr Michael Freeman would like to gratefully acknowledge Dr Chris Del Mar, a previous contributor to this topic.
CDM declares that he has no competing interests.
Brian Swick, MD
Clinical Assistant Professor
University of Iowa College of Medicine
BS declares that he has no competing interests.
Julian Trevino, MD
Associate Professor of Dermatology and Dermatology Residency Program Director
Boonshoft School of Medicine
Wright State University
Speaker's Bureau, Stiefel; Consultant, Abbott.
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