Question

During routine morning rounds in the newborn nursery, a physician evaluates a female infant who developed a diffuse skin eruption at 16 hours of life. The infant was delivered via an uncomplicated vaginal birth at 39 weeks of gestation to a 26-year-old primigravida. Birth weight was $3.2\text{ kg}$ ($7.0\text{ lb}$). Apgar scores were 8 and 9 at 1 and 5 minutes, respectively. Vital signs are temperature $36.9^\circ\text{C}$ ($98.4^\circ\text{F}$), heart rate $142/\text{min}$, and respiratory rate $44/\text{min}$. The infant is alert, active, and feeding vigorously at the breast. Physical examination reveals numerous 2- to 3-mm superficial pustules on a non-erythematous base scattered across the chin, neck, and lower back. Several of the pustules have ruptured, leaving a collarette of fine scale and a central hyperpigmented macule. The remainder of the physical examination is unremarkable. Which of the following is the most appropriate next step in management?