Elevated cerebrospinal fluid nitrite level in human immunodeficiency virus-infected patients with neurosyphilis

Abstract

Human immunodeficiency virus (HIV) and syphilis coinfection is a common phenomenon. A percentage of neurosyphilis cases is asymptomatic in HIV-infected patients. The diagnosis of neurosyphilis is more difficult because of the alteration of cerebrospinal fluid (CSF) presentation by the HIV itself. The CSF levels of the degradation products of nitric oxide (NO; e.g., nitrate and nitrite) are reportedly elevated in animals and patients with bacterial meningitis. We hypothesized that an elevated CSF nitrite concentration may be present in patients coinfected with HIV and neurosyphilis. This cohort study was conducted from January 2007 to June 2008. Forty patients were enrolled and included seven patients in the control group and 33 HIV-infected patients with or without syphilis. Nitrite levels in the serum and the CSF were measured by using the Griess assay. The CSF nitrite levels were significantly higher in HIV-infected patients with neurosyphilis, compared to the control group or patients with HIV infection only or patients with HIV and syphilis coinfection (p = 0.026). The CSF nitrite levels were correlated with the CSF white blood cell counts (Spearman correlation test, r(2) = 0.324; p < 0.001). There was no significant difference between different groups in serum nitrite levels. Marked elevation of CSF nitrite level was observed in HIV-infected patients with neurosyphilis.