Ocular syphilis in an immunocompetent man

A healthy 47-year-old immunocompetent man from Northern Canada presented for ophthalmologic assessment after experiencing one month of right-sided photopsias, floaters, and a right lower nasal quadrant visual field defect. Optic disc swelling, vitritis, chorioretinitis, peripheral retinal infiltrates and hemorrhages were noted in the right eye. A broad right inferior arcuate and nasal visual field defect were also present. Fluorescein angiography of the right retina showed dilated disc vessels and staining of the optic disc. Treponemal antibody testing, using chemiluminescent microparticle immunoassay, was highly positive; this was followed by a Venereal Disease Research Laboratory (VDRL) test with a titre of 1:32 and confirmed by Treponema pallidum particle agglutination (TP-PA) test. Testing did not demonstrate any co-infections. Cerebrospinal fluid (CSF) analysis revealed strong reactivity (4+) to the Treponemal antibody by immunofluorescence antibody absorbed (FTA-ABS) test and non-reactivity by CSF VDRL test. Syphilis PCR of CSF was negative. A diagnosis of neurosyphilis was made. He was treated with ceftriaxone 2 grams IV q24h for 14 days. The vitritis gradually improved. Familiarity with syphilis diagnostics is becoming increasingly important, especially given its recent resurgence amongst several at risk groups. This patient’s case highlights that non-reactive CSF VDRL is not a reliable test in the context of positive serum results and a compatible clinical picture. CSF Treponemal tests such as TP-PA and FTA-ABS offer higher sensitivity than non-treponemal tests such as VDRL in the context of CNS involvement and ocular syphilis.