A 28-month-old boy is brought to the pediatrician for a routine evaluation. The patient was born via vaginal delivery
at 38-weeks of gestational age. The patient’s mother received minimal antenatal care. During the third trimester of pregnancy, the mother had developed a disseminated maculopapular rash involving the palms and soles and arthralgias. The patient’s weight is at the 25th percentile, and head circumference is at the 50th
percentile. Vitals are within normal limits. Abdominal examination reveals hepatosplenomegaly. A depressed nasal bridge, malformed teeth, and bowing of the tibia
are also observed. Cardiovascular examination is unremarkable. Which of the following is the most likely cause of this patient’s condition?