A 6-day-old male infant is brought to the emergency department after an episode of generalized
seizure. He has also experienced
lethargy and
poor feeding. The mother had limited access to
prenatal care. The patient was delivered at home by a midwife. During the third trimester of pregnancy, the mother developed multiple painful
genital lesions that persisted until
labor. Temperature is 40.1°C (104.2°F),
blood pressure is 70/50 mmHg,
pulse is 140/min, and
respiratory rate is 37/min. Weight is at the 20
th percentile, and head circumference is at the 40
th percentile. The anterior fontanelle is open, and facial features appear normal. Ulcerative lesions are present over
the tongue and oral mucosa. Examination of the skin is shown below. A
lumbar puncture is performed, and
cerebrospinal fluid analysis is notable for mononuclear pleocytosis and an elevated protein level. Which of the following agents is most likely responsible for this patient's presentation?
Image reproduced from CDC Public Health Library 
