Spirochetemia due to Treponema pallidum using polymerase-chain-reaction assays in patients with early syphilis: prevalence, associated factors and treatment response

Between 2009 and 2013, polymerase-chain-reaction assay was used to detect Treponema pallidum in the blood samples collected from 296 patients with early syphilis (241 being HIV infected) and 102 patients (34.5%) had spirochetemia. The presence of spirochetemia was associated with lower CD4 counts (per 10-cell/mm3 decrease, adjusted odds ratio (AOR), 1.020; 95% CI, 1.006–1.036) and secondary syphilis (AOR, 4.967; 95% CI, 2.016–12.238). Patients with early latent syphilis were less likely to achieve serological response compared with those with primary or secondary syphilis (AOR, 0.317; 95% CI, 0.142–0.708). However, serological response was not affected by presence of spirochetemia or antibiotic regimens.