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 often more widespread and may be associated with systemic symptoms in severe cases.

Clinically, the key differentiation is the presence of bullae in bullous impetigo versus the crusted erosions without bullae in non-bullous impetigo. Bullous impetigo may require specialist advice or referral due to its potential severity and treatment challenges.

Both forms are caused by Staphylococcus aureus, but bullous impetigo is often associated with strains producing exfoliative toxins.

In summary, look for the presence of bullae (large blisters) to identify bullous impetigo, whereas non-bullous impetigo presents with smaller vesicles that rupture to form honey-coloured crusts.