Question

A $3$-day-old female infant, born at $35$ weeks and $4$ days gestation via emergency cesarean delivery for non-reassuring fetal heart tones, is evaluated in the neonatal intensive care unit for a newly developed skin eruption. Her mother had prolonged rupture of membranes for $22$ hours prior to delivery, and maternal Group B Streptococcus status was unknown. The infant's APGAR scores were $7$ and $8$ at $1$ and $5$ minutes, respectively. Birth weight was $2450\text{ g}$. She is currently feeding adequately through an orogastric tube and is maintaining oxygen saturations of $98\%$ on room air. Current vital signs are: temperature $37.1^\circ \text{C}$ ($98.8^\circ \text{F}$), heart rate $142/\text{min}$, respiratory rate $44/\text{min}$, and blood pressure $62/40\text{ mm Hg}$. Physical examination reveals a widespread rash consisting of superficial $1$- to $2\text{-mm}$ vesicopustules that strictly lack a surrounding erythematous halo. The lesions are prominent on the forehead, anterior neck, and lower back. Gentle wiping of a ruptured pustule reveals a small, collarette-like scale enclosing a hyperpigmented macule. A complete blood count reveals a leukocyte count of $22,000/\text{mm}^3$ with $55\%$ segmented neutrophils, $8\%$ band neutrophils, and $30\%$ lymphocytes. A Wright-stained smear of the pustular contents demonstrates numerous polymorphonuclear leukocytes but no organisms. Based on this patient's clinical presentation, which of the following is the most appropriate next step in management?