Immunoblot and Polymerase Chain Reaction to Diagnose Ocular Syphilis and Neurosyphilis in HIV-positive and HIV-negative Patients.

Purpose: To evaluate immunoblot (IB) and polymerase chain reaction (PCR) to diagnose ocular- and neurosyphilis. Methods: Prospective cross-sectional study. Aqueous humor (AH) and cerebrospinal fluid (CSF) samples were tested for treponemal DNA or antibodies to treponemal antigens. Results: Thirteen of 106 cases had positive syphilis serology of which 69.2% were HIV+ (median CD4+ = 181 cells/µL). Four cases met CDC criteria for neurosyphilis (3 confirmed, 1 probable) and 2 additional cases required neurosyphilis treatment according to UpToDate algorithms. All AH and CSF samples tested PCR negative. Five cases were CSF IB+ and 3 cases AH IB+. Using our classification, eight patients had confirmed neurosyphilis, one had probable neurosyphilis, three had confirmed ocular syphilis and nine had probable ocular syphilis. Conclusion: Our findings suggest that IB of AH and CSF provides additional evidence to diagnose ocular and neurosyphilis and allows us to classify them as probable or confirmed.