Syphilis in HIV-Positive Patients
STD/HIV UPDATE
As we all know, the serologic diagnosis of syphilis is made with two assays done in series. First, serum is screened to detect antibodies that cross-react with treponemal cell surface lipids (VDRL and RPR). Second, serum that is reactive in this screening assay is then re-tested for antibodies specific for Treponema pallidum (FTA-ABS and MHA-TP). Patients with positive screening tests, non-reactive confirmatory tests, and no clinical findings are referred to as biological false-positive (BFP) reactors. They are not considered to have syphilis.
HIV-seropositive patients may have a negative RPR or a negative FTA-ABS, while at the same time have a positive immunoblot analysis for syphilis. Erbelding and colleagues enrolled 1117 study participants of whom 77% were HIV-seropositive.1 Eighty percent of the subjects were RPR-negative, 10% were BFP reactors, and 10% had a serologic diagnosis of syphilis (2 positive assays done in series.) There were no differences between the BFP reactor group and RPR-negative group with respect to age, drug use pattern, or sex for money or drugs.
Three of the five HIV-positive patients with a BFP reaction had positive immunoblots for syphilis. One HIV-positive patient had a negative RPR, but at the same time had a positive immunoblot analysis for syphilis.
COMMENT BY DANIEL D'ALESSANDRO, MD
As a practicing infectious disease physician in our county jail system, I must make treatment decisions on HIV-positive patients with two serologic tests, one visit, and limited follow-up. I don't believe our current serologic tests are totally accurate and reliable based on these data.
Patients in this type of setting may not be treated for syphilis when they actually have syphilis. This, along with the possibility of long-term sequelae in these patients, is alarming to me. The usefulness of immunoblot assays for syphilis needs further study in light of the present limitations of serologic diagnosis of syphilis in HIV-positive patients. (Dr. D'Alessandro is Assistant Professor of Medicine, Robert Wood Johnson Medical School.)
Reference
1. Erbelding EJ, et al. Syphilis serology in human immunodeficiency virus infection: Evidence for false-negative fluorescent treponemal testing. J Infect Dis 1997;176:1397-4000.
You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
- Award-winning Medical Content
- Latest Advances & Development in Medicine
- Unbiased Content