Syphilis and neurosyphilis in human immunodeficiency virus-infected patients: a retrospective study at a teaching hospital in Taiwan.

BACKGROUND AND PURPOSE Some studies have reported that the risk factors for neurosyphilis in patients with human immunodeficiency virus (HIV) and syphilis co-infection, include CD4 cell counts ≤350cells/μL and rapid plasma reagin (RPR) titer ≥1:32. However, neurosyphils can develop even in patients with CD4 cell counts >350cells/μL or RPR titer <1:32. In this study, we evaluated the outcome of syphilis to treatment in HIV-infected patients, and analysed the predictors of neurosyphilis in this population. METHODS We retrospectively reviewed medical records of HIV-infected patients with syphilis who visited the China Medical University Hospital between January 2000 and December 2009. Neurosyphilis was defined by white blood cell (WBC) counts >20cells/μL in the cerebrospinal fluid (CSF) sample or elevated Venereal Disease Research Laboratory (VDRL) titers of the CSF samples. Treatment failure was defined as less than 4-fold decrease in the serum RPR titer at or beyond 12 months post-treatment in case of early syphilis, and, at or beyond 24 months in case of late syphilis. RESULTS One hundred and twenty-one HIV-infected patients (average age, 32 years) with syphilis were included in this study. Of 63 patients who had follow-up of serologic responses, 30 (47.6%) failed to respond to treatment. CD4 cell counts ≤200cells/μL was the indicator for treatment failure (P=.029). Lumbar puncture was performed in 65 patients, and 14 patients were diagnosed with neurosyphilis. At the time of lumbar puncture, 31 and 19 of the 65 patients showed CD4 cell counts of >350cells/μL and RPR of <1:32, respectively. An HIV viral load (VL) ≥10000copies/mL was found to be associated with the development of neurosyphilis (P=.016). CONCLUSION In HIV-infected patients with syphilis, RPR titer should be evaluated more frequently when CD4 count ≤200cell/μL is associated with treatment failure. Lumbar puncture for the diagnosis of neurosyphilis should be considered in patients with HIV and syphilis co-infection, even in patients with CD4 cell counts >350cells/μL, and particularly when the HIV VL ≥10000copies/mL.