Syphilis in HIV-infected patients

Diagnostic Notes

Unusual serologic responses have been observed in HIV-infected patients with syphilis. Most reports indicate higher than expected titers, but false-negative results and delayed onset of seroreactivity have also been reported. However, both treponemal and nontreponemal serologic tests for syphilis are interpreted in all HIV-infected patients with syphilis in the same way as in HIV-uninfected individuals.

If clinical examination confirms syphilis but serologic tests are negative or equivocal, alternative tests such as lesional biopsy, darkfield imaging, or DIF of lesional tissue may be useful.

In HIV-infected patients, the possibility of neurosyphilis must be considered in the differential diagnosis of nervous system diseases.

Treatment

Published case reports and expert opinion suggest that HIV-infected patients with early syphilis have an increased risk of developing neurologic complications and treatment failure with conventional regimens. The level of risk, although uncertain, is small. There is no evidence that any other regimen is more effective in preventing neurosyphilis than regimens recommended for patients without HIV infection. Follow-up after treatment is essential.

Primary and secondary syphilis in HIV-infected patients

Treatment

The same treatment with benzathine penicillin G, 2.4 million units IM, is recommended as for HIV-negative patients. Some experts recommend additional treatment, such as multiple doses of benzathine penicillin G, as for late syphilis, or other antibiotics in addition to the 2.4 million units IM benzathine penicillin G.

Other considerations for patient management

Abnormalities in CSF are frequently found in asymptomatic HIV-infected patients without syphilis and in HIV-uninfected patients with primary or secondary syphilis. However, the prognostic significance of these abnormalities in HIV-infected patients with primary or secondary syphilis is unknown. Most HIV-infected patients respond appropriately to commonly recommended penicillin treatment; however, some experts recommend examining CSF before initiating therapy and modifying the regimen accordingly.

Follow-up observation

Clinical and serological monitoring is performed in HIV-infected patients after 1 month, and then after 2, 3, 6, 9 and 12 months after completion of treatment. Some experts recommend repeating the CSF test after completion of therapy (e.g. after 6 months).

In HIV-infected patients, CSF testing is necessary if treatment is ineffective; they should be retreated as for patients without HIV infection. CSF testing and retreatment are also necessary in patients with primary and secondary syphilis whose nontreponemal antibody titers do not decrease by a factor of 4 within 3 months of completion of treatment. If CSF titers are normal, most experts recommend retreatment with benzathine penicillin G, 7.2 million units (3 weekly doses of 2.4 million units).

Special Notes

Allergy to penicillin

HIV-infected patients with primary or secondary syphilis who are allergic to penicillin should be managed in the same way as HIV-uninfected patients.

Latent syphilis in HIV-infected patients

Diagnostic Notes

HIV-infected patients with early latent syphilis should be managed and treated in the same way as HIV-negative patients with primary and secondary syphilis.

In HIV-infected patients with either late latent syphilis or syphilis of unknown duration, CSF should be examined before treatment.

Treatment

HIV-infected patients with late latent syphilis or syphilis of unknown duration and normal CSF results may be treated with benzathine penicillin G, 7.2 million units (3 weekly doses of 2.4 million units per week). Patients with CSF results consistent with neurosyphilis should be managed and treated as recommended for neurosyphilis.

Follow-up observation

Clinical and serological monitoring is performed at 6, 12, 18 and 24 months after completion of treatment. If clinical symptoms develop during this period or nontreponemal test titers increase 4-fold, CSF should be re-examined and appropriate treatment should be administered. If nontreponemal test titers decrease by less than 4-fold between 12 and 24 months, CSF should be re-examined and appropriate treatment should be administered.

Special Notes

Allergy to penicillin

In HIV-infected patients, penicillin regimens should be used at all stages of syphilis. Skin testing can be used to confirm penicillin allergy (see Management of Patients with Penicillin Allergy). Patients can be desensitized and then treated with penicillin.