Aetiology of boils and carbuncles

Boils (furuncles) and carbuncles (boils with multiple heads) are cutaneous abscesses that are associated with hair follicles and extend into the subcutaneous tissue. They are tender and painful, but seldom cause systemic symptoms. Boils and carbuncles can occur in clusters on the axillae, groin or buttocks.

Boils and carbuncles are usually caused by Staphylococcus aureus, occasionally in combination with Streptococcus pyogenes (group A streptococcus [GAS]).

Hidradenitis suppurativa is an important noninfectious differential diagnosis of acute furunculosis.

Patients who inject drugs may have infection caused by other pathogens and are at increased risk of methicillin-resistant Staphylococcus aureus (MRSA) infection; for considerations, see Factors impacting likely pathogens involved in skin and soft tissue infections and bacterial endocarditis in people who inject drugs.