(526) Congenital syphilis risk following inadequate treatment of late latent or unknown duration syphilis in pregnancy

Of 362 individuals with late latent syphilis, 51(14.1%) received inadequate treatment and 311(85.9%) received adequate treatment before delivery. Inadequately treated individuals had fewer prenatal visits  (4 vs 11, p< 0.001) and later EGA at syphilis diagnosis (23 vs.14 weeks, p < 0.001). Inadequately treated individuals received the first BPG dose at a later EGA than adequately treated (27 vs. 15.7 weeks, p < 0.001). Serologic response (fourfold RPR drop) occurred in 11(22%) with inadequate vs 110 (35%) with adequate treatment (p=0.05). Neonates born to mothers who received inadequate syphilis treatment delivered earlier (38 vs. 39 weeks, p = 0.01). CS was higher among inadequately treated (OR 2.16, 95% CI: 0.87–4.93) but effect was not statistically significant. Neonates born to inadequately treated mothers were significantly more likely to receive 10 days IV penicillin. Stratified by initial RPR titer, CS risk increased with maternal RPR group, but risks were imprecise and not statistically significant.

Conclusion:

While the great majority of gravidas with latent syphilis are adequately treated, data on congenital syphilis risk following inadequate treatment of late latent syphilis are relatively weak. Refinement of clinical criteria for determining the highest risk neonates could be considered.