Final answer:
The condition described in the question is atopic dermatitis, also known as eczema, a type of allergic reaction resulting in a characteristic skin rash which in this scenario is complicated by a secondary bacterial infection.
Step-by-step explanation:
The condition described in the student's question is atopic dermatitis, also commonly known as eczema. This is a type of allergic reaction that shows up as a moist, erythematous (reddened) rash on areas such as the cheeks, chest, and extensor surfaces of the arms, as described in the case of the 5-month-old infant, J.W. When eczema is accompanied by a secondary bacterial infection, it may require additional treatment beyond the usual care for eczema, which can include moisturizers and corticosteroid creams. Eczema can lead to dry, itchy patches of skin that may swell, flake, and in severe cases, even bleed. Although both 'atopic dermatitis' and 'eczema' are used to describe this condition, it is not to be confused with other skin disorders such as psoriasis or contact dermatitis.