Treponema pallidum, a spirochete, causes syphilis and is spread through ... In our case, an increase in the patient's RPR titer by 4-fold (from 1:2 to 1:8) was deemed to be evidence of potential ...

Data from a large study of syphilis indicate a high rate of neurosyphilis in HIV-infected patients with a CD4-cell count less than or equal to 350 or a serum RPR titer ... an 18.6-fold higher ...