How can I differentiate between non-bullous and bullous impetigo in a clinical setting?

Non-bullous impetigo typically presents with small vesicles or pustules that rupture quickly to form characteristic honey-coloured crusted erosions on an erythematous base. It is the more common form and usually affects exposed areas such as the face and limbs.

Bullous impetigo, in contrast, is characterised by larger, fragile bullae (blisters) filled with clear or yellow fluid that rupture to leave a thin brown crust. These bullae are caused by exfoliative toxins produced by Staphylococcus aureus and are more commonly seen in infants and young children.

Clinically, the presence of bullae distinguishes bullous impetigo from the non-bullous form, which lacks these larger blisters and instead shows crusted erosions from ruptured vesicles or pustules.

Referral or specialist advice should be considered for bullous impetigo or impetigo that recurs frequently, as it may be more difficult to treat and potentially more serious.

In summary, the key clinical difference is the presence of bullae in bullous impetigo versus crusted erosions without bullae in non-bullous impetigo.

This differentiation guides treatment decisions and the need for referral.

¹