ABSTRACT
Persistent non-treponemal titres after treatment are common among patients with latent syphilis. Although retreatment is often done in clinical practice, optimal management remains uncertain due to the paucity of data regarding serological response to retreatment and long-term outcomes. We compared the serological responses of serofast latent syphilis patients retreated with 7.2 million units of benzathine penicillin with the responses of patients who did not receive retreatment (control group). We retrospectively analysed the serological response to therapy following retreatment of 35 serofast latent syphilis patients at 12 months with benzathine penicillin 2.4 million units weekly for 3 weeks. In all, 74.3% (26/35) of the cases with latent syphilis who failed to achieve serological cure at 12 months after initial therapy achieved serological cure after retreatment and after an additional 12 months of follow-up. However, statistically similar serological cure rate was observed in 80.0% (28/35) of the control group (p > .05). Our findings illustrate no improvement in serological response among serofast latent patients retreated with three doses of benzathine penicillin.
Subject(s)
Anti-Bacterial Agents/therapeutic use , Penicillin G Benzathine/administration & dosage , Syphilis, Latent/drug therapy , Syphilis/drug therapy , Adult , Case-Control Studies , Dose-Response Relationship, Drug , Female , Humans , Male , Penicillin G Benzathine/therapeutic use , Retreatment , Retrospective Studies , Syphilis/blood , Syphilis/diagnosis , Syphilis Serodiagnosis , Syphilis, Latent/blood , Time Factors , Treatment Failure , Treatment OutcomeABSTRACT
BACKGROUND: Tp15, Tp17, Tp45, and Tp47 are outer-membrane proteins found in Treponema pallidum, the etiologic agent of syphilis. These proteins are potent antigens and are potential markers for the serological detection of syphilis. The present study analyzed antibodies to these protein antigens (TP-IgM and TP-IgG) in human serum and investigated the expression of these antibodies during different stages of syphilis. METHODS: Serum samples were collected from 69 subjects (male 45, female 24) diagnosed with syphilis and analyzed by Western blotting for the expression of IgM and IgG against the four protein antigens. Expression levels of the target antibodies were compared during the same stage of syphilis as well as between different stages of this disease. RESULTS: In subjects with primary syphilis, the positive rate of Tp45 IgM was higher than that of other TP-IgM. Tp15 IgM was detected only in subjects with tertiary syphilis. Similarly, the seroprevalence of Tp45 IgG in primary syphilis was higher than for other TP-IgG. No target TP-IgM was detected in subjects with latent syphilis. In subjects with secondary syphilis, the expression level of Tp15 IgG (138.73 ± 20.16) was higher than for other target TP-IgG. In subjects with tertiary syphilis, all target TP-IgG were detected. In subjects with tertiary or latent syphilis, the expression levels of Tp45 IgG (121.33 ± 11.04 and 110.10 ± 40.19, respectively) were higher than those of other target TP-IgG. The expression levels of all Tp-IgM were similar before or after anti-syphilis treatment. In comparison, the expression levels of all TP-IgG decreased compared with the pre-treatment levels, and this decrease was statistically significant (both P < 0.05) for Tp17 IgG and Tp47 IgG. CONCLUSIONS: After Treponema pallidum infection, Tp45 IgM appeared first and Tp15 IgM occurred during later stages. The positive rates of all TP-IgG increased with the duration of this disease. Anti-syphilis treatment reduced the expression levels of Tp17 IgG and Tp47 IgG. Larger-scale studies are required to further validate the value of Tp15, Tp17, Tp45, and Tp47 as markers for the early detection of primary and latent syphilis.
