Response to standard syphilis treatment in patients infected with the human immunodeficiency virus.

In a study designed to evaluate the efficacy of penicillin in HIV-infected patients with syphilis and to determine the clinical and laboratory responses after treatment, 13 patients with HIV infection and syphilis were assessed at enrollment and at the last follow-up examination (median time of 21 months). The Venereal Diseases Research Laboratory (VDRL) test, the Treponema pallidum hemaglutination test, and leukocyte counts in cerebrospinal fluid were evaluated both at enrollment and at the last follow-up visit, and the polymerase chain reaction for Treponema pallidum DNA and the rabbit infectivity test were performed on cerebrospinal fluid samples at the last follow-up visit. Primary syphilis was confirmed in four patients, latent syphilis in five, and neurosyphilis in four. After penicillin treatment, all patients were asymptomatic. The serum rapid plasma reagin test became negative in five patients, and titers declined in eight. The VDRL test, Treponema pallidum DNA, and the rabbit infectivity test were negative in all 13 patients. Except for one patient whose serological titer was slow to decline, all patients had good clinical and serological responses to penicillin. In certain settings, factors other than penicillin treatment failure should be considered in HIV-infected patients with suspected relapse of syphilis.