Are We Playing It Fast and Loose With the Serofast?

Abstract

Four infants (one singleton and a set of triplets) born to mothers with serofast reactive plasma reagin at 1:4 to 1:8 were found to have congenital syphilis. Each mother had a history of receiving appropriate treatment for their syphilis stage at the time of diagnosis with benzathine penicillin G 2.4 million units intramuscularly weekly 3 times. Both exhibited a 4-fold decrease in their reactive plasma reagin titer. The singleton was asymptomatic but found to have long bone radiographic evidence for congenital syphilis. Of the triplets, one had laboratory abnormalities and a rash, while all 3 triplets had radiographic findings of congenital syphilis. All were treated with 10-14 days of intravenous penicillin G according to the Centers for Disease Control and Prevention treatment guidelines. These cases highlight that infants may be at risk for congenital syphilis, despite being classified as "congenital syphilis unlikely" according to current syphilis practice guidelines. A thorough maternal history and complete infant physical evaluation at birth is recommended for all neonates born to mothers diagnosed with and treated for syphilis. Close follow-up with repeat nontreponemal titers, as outlined by the Centers for Disease Control and Prevention and American Academy of Pediatrics guidelines, is recommended.

FIGURE 1.

Serologic response to infection with Treponema pallidum.

FIGURE 2.

A: Radiograph of the right forearm demonstrates cupping of the distal radial metaphysis as well as periostitis (black arrow). B: Radiograph of the right tibia and fibula demonstrates irregularity of the distal tibial and fibular metaphyses (black arrow). C: Radiograph of the left femur demonstrates loss of mineralization in the distal femoral metaphysis as well as loss of the zone of provisional calcification in the subchondral bone (black arrows).

FIGURE 3.

Radiographs (A–C), (D–F) and (G–I) correspond to triplet A, B and C, respectively. A: Radiograph of the left tibia and fibula demonstrates a celery stalk appearance of the distal tibia and fibula (black arrow) and subchondral lucent band in the proximal tibial metaphysis (black arrowhead). B: Radiograph of the left femur demonstrates demineralization of both the proximal and distal femoral metaphyses with irregularity of the distal metaphysis (black arrow). C: Lateral radiograph of the left foot demonstrates double density in the calcaneus (black arrow), which could represent disrupted mineralization associated with congenital syphilis. D: Radiograph of the right forearm demonstrates cupping of the distal ulnar metaphysis with mixed lucency and sclerosis in both the distal radial and ulnar metaphyses (black arrow). E: Radiograph of the right humerus demonstrates slight irregularity of the distal humeral metaphysis with some central lucency (black arrow) as well as some generalized demineralization of the proximal humeral metaphysis. F: Radiograph of the right hand demonstrates mild demineralization of the metaphyses of multiple bones with some irregularity most prominent in the middle phalanges (black arrows). G: Radiograph of the right femur demonstrates irregularity of the distal right femoral metaphysis (black arrow). H: Radiograph of the right forearm demonstrates sclerosis and irregularity of the distal radial and ulnar metaphyses with some cupping of the distal ulnar metaphysis (black arrow). I: Radiograph of the left tibia and fibula demonstrate a celery stalk appearance of the distal metaphyses with coarsened trabecula, irregularity of the metaphysis and sclerosis (black arrow).

FIGURE 4.

Neonatal immunoglobulin by age.