Bullous impetigo is related to which organism?

• A. Streptococcus pyogenes
• B. Escherichia coli
• C. Staphylococcus aureus
• D. Klebsiella pneumoniae

Answer: (C)

Bullous impetigo is caused by Staphylococcus aureus through its exfoliative toxins, which cleave desmoglein-1 in the superficial epidermis (the stratum granulosum). This toxin activity weakens intercellular connections, producing the characteristic flaccid bullae that contain clear fluid and rupture easily, leaving crusts. Streptococcus pyogenes can cause impetigo too, but typically nonbullous and not due to the exfoliative toxins that create these bullae. Escherichia coli and Klebsiella pneumoniae are not usual culprits in impetigo. So the organism best associated with bullous impetigo is Staphylococcus aureus.