Impetigo and Staphylococcal Skin Infections

A 4-year-old boy from rural Maharashtra presents with his mother to the outpatient clinic with multiple fluid-filled blisters on his left forearm and hand that appeared 3 days ago. The lesions are preceded by a small cut sustained while playing. On examination, there are honey-crusted erosions overlying erythematous patches. The child is afebrile. A Gram stain of the blister fluid shows Gram-positive cocci in clusters. What is the most likely causative organism and the recommended first-line treatment?

Which exotoxin produced by Staphylococcus aureus is responsible for the formation of bullae in bullous impetigo?