This patient most likely has allergic contact dermatitis from the neomycin. Neomycin is a commonly used over-the-counter topical aminoglycoside antibiotic (often used either alone or as part of combination topical antibiotic preparations). With repeated use, especially on abraded or lacerated skin, neomycin can lead to contact sensitization, which is a T-cell mediated hypersensitivity reaction. Patients and clinicians often mistake this for a wound infection, but if the area is pruritic and there is a geometric, well-defined pattern generally corresponding with the contact area, a contact allergy should be suspected. Discontinuation of the medication and future avoidance are generally recommended.

Group A streptococcal infections would cause skin infections such as impetigo, cellulitis, or erysipelas. This patient has no pain, wound drainage, or discharge that could be associated with bacterial impetigo. There is no pain or lymphangitic streaking typical of cellulitis. Erysipelas would appear as violaceous-red, edematous, well-demarcated plaques on the face or lower extremities, unlike this patient's presentation.

The classic presentation of herpes simplex virus infection is a group of painful, small vesicles on an erythematous base, transitioning to pustules and subsequent crusting of the lesions over time. Herpetic infection would be painful with no pruritus.

Staphylococcus aureus infection would present with eczematous plaques and open erosions on the flexural folds with pustules in those areas, not in a geometric pattern on a compromised skin barrier typical of allergic contact dermatitis.