Final answer:
Inflammatory lesions are the most responsive to topical antibiotic therapy in acne vulgaris, as they are often caused by bacterial infections that the antibiotics can target.
Step-by-step explanation:
The lesions that respond most effectively to topical antibiotic therapy in treating acne vulgaris are Inflammatory lesions.
Topical antibiotics are designed to target the bacteria causing inflammation, such as Propionibacterium acnes, which leads to the formation of inflammatory lesions when it infects hair follicles clogged with dead skin cells and sebum. These inflammatory lesions can include papules, pustules, nodules, or cysts. In contrast, open comedones (blackheads) and superficial lesions do not benefit as much from antibiotic treatment, as they are not primarily caused by a bacterial infection.
Cysts, being deeper and more severe forms of inflammatory acne, often require more aggressive treatment methods.