BACKGROUND: From 2012 to 2015, the CDC reported an increase in congenital syphilis (CS) cases. Reverse sequence (RS) testing is reported as a high throughput and cost effective method for syphilis screening. RS testing starts with a treponemal specific antibody test (e.g. chemiluminescent immunoassay [CIA]), then reflexive testing with a non-treponemal antibody test (rapid plasma reagin [RPR]) when CIA is positive. In cases with discordant results (e.g., CIA positive, RPR negative), a different second treponemal specific antibody test is performed (e.g. fluorescent treponemal antibody [FTA]). However, when discordant maternal test results occur, clinicians may be unsure about the evaluation and management of infants born to these mothers. OBJECTIVE: To examine the utility of a clinical algorithm designed to evaluate infants at risk for congenital syphilis in the context of RS testing. DESIGN/METHODS: We performed a retrospective study from December 2011 to May 2014 at an urban tertiary center where RS testing was available and an expert opinion algorithm was implemented (see figure). Any infant with a positive CIA, or born to a mother with a positive CIA was identified. The clinical evaluation and management of these infants were recorded and compared to the algorithm. When available, infant follow-up was examined up to 6 months of age to assess for any missed congenital syphilis cases. RESULTS: 63 infants were identified. 26 (41.3%) were born to mothers with true positive results (CIA positive, RPR positive); 16 (25.4%) were born to mothers with presumed false positive results (CIA positive, RPR negative, FTA negative); and 21 (33.3%) were born to mothers with truly discordant results (CIA positive, RPR negative, FTA positive). Within the true positive and presumed false positive groups, clinical evaluation was in agreement with the clinical algorithm in 85-94% of the cases. In contrast, only 5 infants (24%) in the truly discordant group were evaluated according to the algorithm. There were no known missed cases of congenital syphilis among the 13 infants (62%) in the discordant group who were not evaluated. CONCLUSIONS: There is no standard management for infants at risk for CS in a RS testing system. In this study, despite an established algorithm, the evaluation of infants born to mothers with discordant RS results remained inconsistent. Among the infants whose management deviated from the algorithm, clinical judgment played a paramount role.

Figure 1

Congenital Syphilis Clinical Algorithm, Part 1

Part 1 of the congenital syphilis clinical algorithm

Figure 1

Congenital Syphilis Clinical Algorithm, Part 1

Part 1 of the congenital syphilis clinical algorithm

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Figure 2

Congenital Syphilis Clinical Algorithm, Part 2

Part 2 of the congenital syphilis clinical algorithm

Figure 2

Congenital Syphilis Clinical Algorithm, Part 2

Part 2 of the congenital syphilis clinical algorithm

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