Factors associated with syphilis treatment failure and reinfection: a longitudinal cohort study in Shenzhen, China

Syphilis Serologies: A Practical Approach for the Primary Care Clinician

Syphilis serology interpretation can be challenging even for experienced providers. This article reviews the staging of syphilis and the principles of syphilis serology testing, the algorithms used in diagnosis, and guidance for their use in monitoring the response to treatment. The authors illustrate these principles through a series of clinical scenarios and describe the rationale behind the management approaches.

Reduced Risk of Syphilis Reinfection in Men Interviewed by Disease Intervention Specialists: A Pilot Study

Introduction

Syphilis is a highly transmissible sexually transmitted infection. Rising rates of infection and reinfection are of great concern to public health officials. In local health departments across the U.S., disease intervention specialists attempt to interview all people diagnosed with early syphilis, to elicit sexual partner information, and to trace and treat the partners. This method of interviewing and contact tracing is an evidence-based practice that reduces the spread of the disease in the community, but few studies address the relationship between the disease intervention specialists' interviews and index patient reinfections. We hypothesized that patients who were interviewed, patients who provided partner information, and patients with more treated partners would have a reduced risk of reinfection.

Methods

Our sample consisted of 82 men listed in the Suffolk County Department of Health Services syphilis log who were diagnosed with primary, secondary, or early latent syphilis. We determined whether and when the patients were reinfected during a set time period, from 2016 to 2020. Kaplan-Meier analyses with log-rank statistics and Cox hazard proportional models were used to calculate time to reinfection and hazard ratios.

Results

Although none of the models produced p<0.05, notable trends were observed. In subset analyses of interviewed patients, 23.8% of patients who named partners were reinfected during the study period, whereas 50% of those who did not name partners were reinfected during that time. In addition, the hazard ratio for index patients who named partners was 0.51 (95% CI=0.225, 1.170, p=0.113). When some or all the patients' partners were treated, 20% were reinfected by the end of the study, whereas 33.3% of cases with no partners treated were reinfected by the end of the study. The hazard ratio for patients with some or all partners treated was 0.48 (95% CI=0.136, 1.711, p=0.258).

Conclusions

Although none of the results was statistically significant, trends suggest that partner elicitation and partner treatment status could be associated with reduced risk of syphilis reinfection. Because this pilot study utilized a small convenience sample that was not tested for statistical power, we could not adequately address these trends. Future studies, with larger sample sizes, should address these relationships.

Syphilis vaccine: challenges, controversies and opportunities

Syphilis is a sexually or vertically (mother to fetus) transmitted disease caused by the infection of Treponema pallidum subspecie pallidum (TPA). The incidence of syphilis has increased over the past years despite the fact that this bacterium is an obligate human pathogen, the infection route is well known, and the disease can be successfully treated with penicillin. As complementary measures to preventive campaigns and early treatment of infected individuals, development of a syphilis vaccine may be crucial for controlling disease spread and/or severity, particularly in countries where the effectiveness of the aforementioned measures is limited. In the last century, several vaccine prototypes have been tested in preclinical studies, mainly in rabbits. While none of them provided protection against infection, some prototypes prevented bacteria from disseminating to distal organs, attenuated lesion development, and accelerated their healing. In spite of these promising results, there is still some controversy regarding the identification of vaccine candidates and the characteristics of a syphilis-protective immune response. In this review, we describe what is known about TPA immune response, and the main mechanisms used by this pathogen to evade it. Moreover, we emphasize the importance of integrating this knowledge, in conjunction with the characterization of outer membrane proteins (OMPs), to expedite the development of a syphilis vaccine that can protect against TPA infection.

Lumbar puncture for neurosyphilis investigation in asymptomatic patients with HIV-syphilis coinfection: a cross-sectional study among infectious disease specialists

BACKGROUND

Syphilis is a major public health issue worldwide. In people living with human immunodeficiency virus (PLHIV), there are higher incidences of both syphilis and neurosyphilis. The criteria for referring PLHIV with syphilis for lumbar puncture is controversial, and the diagnosis of neurosyphilis is challenging.

OBJECTIVE

To describe the knowledge, attitudes, and practices of infectious disease specialists and residents in the context of care for asymptomatic HIV-syphilis coinfection using close-ended questions and case vignettes.

DESIGN AND SETTING

Cross-sectional study conducted in three public health institutions in São Paulo (SP), Brazil.

METHODS

In this cross-sectional study, we invited infectious disease specialists and residents at three academic healthcare institutions to answer a self-completion questionnaire available online or in paper form.

RESULTS

Of 98 participants, only 23.5% provided answers that were in line with the current Brazilian recommendation. Most participants believed that the criteria for lumbar puncture should be extended for people living with HIV with low CD4+ cell counts (52.0%); in addition, participants also believed that late latent syphilis (29.6%) and Venereal Disease Research Laboratory (VDRL) titers ≥ 1:32 (22.4%) should be conditions for lumbar puncture in PLHIV with no neurologic symptoms.

CONCLUSION

This study highlights heterogeneities in the clinical management of HIV-syphilis coinfection. Most infectious disease specialists still consider syphilis stage, VDRL titers and CD4+ cell counts as important parameters when deciding which patients need lumbar puncture for investigating neurosyphilis.

Syphilis Infections, Reinfections and Serological Response in a Large Italian Sexually Transmitted Disease Centre: A Monocentric Retrospective Study

Background: Syphilis infection does not confer definitive and protective immunity against reinfection, and crucial aspects of repeated episodes of syphilis are far from being understood, especially among people living with HIV (PLWH). Methods: In order to explore the burden of syphilis in a large cohort of HIV-negative patients and PLWH, this retrospective study describes the demographics, clinical presentation and treatment outcome of patients with syphilis treated at our clinic from 2013 to 2021. Results: Within the study period, 1859 syphilis episodes (827, 44.5% first infections and 1032, 55.5% reinfections) were recorded. A total of 663 patients, of whom 347 (52%) had PLWH, were considered. Syphilis was mostly diagnosed in males (77%) and European (79%) patients. More than half of syphilis episodes were recorded during the late latent stage (64%) or during follow-up/screening visits for other diseases, while symptomatic stages led to a diagnosis in almost half of HIV-negative patients (p < 0.001). PLWH with syphilis infection were predominantly homo/bisexual (p < 0.001). A significantly higher rate of syphilis reinfection was observed in PLWH, who also demonstrated a higher range of subsequent episodes. The serofast state was found to be similar at the 6- and 12-month follow-up visits. The multivariate analysis carried out in the HIV-positive group showed that an RPR titre >1:16 was an independent predictor for serological non-response. Conclusions: Syphilis reinfections are predominantly diagnosed in HIV-positive MSM. The high rate of asymptomatic presentation among PLWH supports the role of periodical syphilis screening. In PLWH, the only baseline factor associated with an increased risk of non-response was an RPR titre >1:16, while assessment at 12 months after treatment increased the possibility of detecting a serological response, indicating that PLWH have a slower serological response to treatment.

Preconception syphilis seroprevalence and association with duration of marriage and age among married individuals in Guangdong Province, China: A population-based cross-sectional study

BACKGROUND

Duration of marriage (DoM) and age are important characteristics of married individuals, who are the critical population for eliminating mother-to-child transmission (MTCT) of syphilis. A deep understanding of the preconception syphilis seroprevalence (PSS) and its distribution among this population may be able to help to eliminate MTCT. However, few population-based epidemiological studies have been focused on this group, and the association of DoM and age with PSS remains unclear.

METHODOLOGY/PRINCIPAL FINDINGS

This study used data from 4,826,214 married individuals aged 21-49 years who participated in the National Free Preconception Health Examination Project in Guangdong Province, China, between 2014 and 2019. Syphilis was screened using the rapid plasma reagin (RPR) test. The seroprevalence time series, seroprevalence map, and hot spot analysis (HSA) were employed to visualize the spatiotemporal distribution. The restricted cubic spline (RCS) based on multivariate logistic regression was used to model the association of DoM and age with PSS. The interactions on the additive scale of DoM and age were also assessed. The PSS was 266.61 per 100,000 persons (95% CI: 262.03-271.24) and the burden was higher in economically underdeveloped area within the province. A strong J-shaped non-linearity association was observed between age and PSS. Specifically, the risk of seropositivity was relatively flat until 27 years of age among men and increased rapidly afterwards, with an adjusted odds ratio (aOR) of 1.13 (95% CI: 1.12-1.13) per unit. Among women, the risk of seropositivity was relatively flat until 25 years of age and increased rapidly afterwards with an aOR of 1.08 (95% CI: 1.08-1.09) per unit. DoM was negatively associated with PSS among married individuals. Moreover, the combined effects of age and DoM appeared to be synergistic.

CONCLUSIONS/SIGNIFICANCE

Our findings suggest that attention should be paid to preventing syphilis in underdeveloped areas and that syphilis screening in newly married individuals who are in their late 20s or older should be recommended. Additionally, early syphilis prevention strategies should be implemented among young people as early as possible.

Factors Associated With Neurosyphilis in Patients With Syphilis Treatment Failure: A Retrospective Study of 165 HIV-Negative Patients

Background

In recent years, the incidence of syphilis has increased year by year. Our study is to explore the risk factors for the development of neurosyphilis in patients who failed syphilis treatment.

Methods

A total number of 165 patients with complete medical records and who agreed to undergo lumbar puncture were divided into 47 neurosyphilis cases and 118 non-neurosyphilis cases according to the diagnostic criteria of neurosyphilis, and the differences in clinical characteristics and laboratory features between the two groups were analyzed. Significant variables were entered into multivariable logistic regression models.

Results

(1) There were statistical differences (p < 0.05) between the neurosyphilis (NS) group and the non-neurosyphilis (NNS) group in terms of the higher proportion of male and serum rapid plasma reagin (RPR) > 1:32 and the elevated cerebrospinal fluid white blood cell (CSF WBC) and CSF protein in the neurosyphilis group compared with the non-neurosyphilis group. (2) Male gender, serum RPR titers >1:32 at lumbar puncture, CSF WBC >8 × 10⁶/L were significantly associated with neurosyphilis.

Conclusion

For patients who have failed syphilis treatment, lumbar puncture should be performed to exclude neurosyphilis, to enable early diagnosis and treatment, and to prevent irreversible damage of neurosyphilis, especially if the patient is male and has a serum RPR>1:32 and elevated CSF WBC at lumbar puncture, which are risk factors for neurosyphilis.

Management of Adult Syphilis: Key Questions to Inform the 2021 Centers for Disease Control and Prevention Sexually Transmitted Infections Treatment Guidelines

A panel of experts generated 5 "key questions" in the management of adult syphilis. A systematic literature review was conducted and tables of evidence were constructed to answer these questions. Available data suggest no clinical benefit to >1 dose of benzathine penicillin G for early syphilis in human immunodeficiency virus (HIV)-infected patients. While penicillin remains the drug of choice to treat syphilis, doxycycline to treat early and late latent syphilis is an acceptable alternate option if penicillin cannot be used. There are very limited data regarding the impact of additional antibiotic doses on serologic responses in serofast patients and no data on the impact of additional antibiotic courses on long-term clinical outcomes. In patients with isolated ocular or otic signs and symptoms, reactive syphilis serologic results, and confirmed ocular/otic abnormalities at examination, a diagnostic cerebrospinal fluid (CSF) examination is not necessary, because up to 40% and 90% of patients, respectively, would have no CSF abnormalities. Based on the results of 2 studies, repeated CSF examinations are not necessary for HIV-uninfected patients or HIV-infected patients on antiretroviral therapy who exhibit appropriate serologic and clinical responses after treatment for neurosyphilis. Finally, several important gaps were identified and should be a priority for future research.

Predictors of Seronegative Conversion After Centralized Management of Syphilis Patients in Shenzhen, China

Objective: The aim of this study was to explore the seronegative conversion status of syphilis patients after centralized management and to analyze potential determinants.

Materials and Methods: A retrospective population-based cohort study was conducted, and data for individuals who had been diagnosed with syphilis between 2011 and 2019 were retrieved from the Shenzhen Nanshan Center for Chronic Disease Control. Seroconversion statuses were summarized as percentages. Univariable and multiple Cox proportional hazard regression models were used to analyze the factors associated with seronegative conversion among syphilis patients.

Results: During the study period, 1,545 patients with syphilis participated in the syphilis convergence case management program on a voluntary basis, of whom 290 were excluded due to missing follow-up data. A total of 27.6% (346/1255) of patients with syphilis showed seronegative conversion. Multivariable analysis revealed that the following significantly determined syphilis seroconversion from positive to negative: younger age (15–19 years vs. ≥30 years: HR = 2.18), male gender (HR = 1.45), lower baseline toluidine red unheated serum test (TRUST) titer of ≤ 1:8 (HR = 2.23), and different disease stages, including latent syphilis (HR = 1.98), primary syphilis (HR = 7.67), and secondary syphilis (HR = 4.83).

Conclusions: Few patients with syphilis tested negative after treatment at the end of the study. Seronegative conversion in the patients was associated with age, sex, baseline TRUST titer, and syphilis stage.

Clinical presentation and serological diagnosis of syphilis reinfection in men living with HIV: a retrospective cohort study

OBJECTIVES

Studies on the characteristics of syphilis reinfection are scarce despite increasing numbers and proportions of cases. We aimed to gain insights into the clinical and serological presentation of reinfected men living with HIV and to evaluate diagnostic criteria for syphilis reinfection.

METHODS

We conducted a retrospective cohort study of 259 HIV-positive men diagnosed with syphilis between January 1999 and September 2015 at the University Hospital Zurich. We compared patients with a single syphilis infection (n=109) to patients with reinfections (n=150).

RESULTS

The two groups matched in age, sexual orientation and numbers of other STIs. Reinfected patients more often presented with latent syphilis than patients with a single syphilis episode (41.9% vs 8.9%; p<0.001). Although generally high venereal diseases research laboratory (VDRL) or rapid plasma reagin (RPR) titres (median 1:32) were seen in reinfected patients, 19.4% had titres ≤1:8. Treponema pallidum passive particle agglutination (TPPA) titres were significantly higher (1:81 840 vs 1:10 240; p<0.001), while IgM values were significantly lower (1.27 vs 3.5; p<0.001) in syphilis reinfections than in first infections. The TPPA increased ≥fourfold in >92.3% of reinfected patients.

CONCLUSIONS

Our data highlight the paramount importance of regularly screening patients at risk as syphilis reinfections in men living with HIV are more likely to be latent infections, that is, without symptoms. As non-treponemal tests might be biologically false-positive (up to a titre of 1:8) due to various conditions, a ≥fourfold increase of the TPPA might be considered as optional criterion for the diagnosis of syphilis reinfections. This could be especially valuable for diagnosing reinfected latent stage patients.

Predictors of serofast state after treatment for early syphilis in HIV-infected patients

OBJECTIVES

Non-treponemal serological tests are used to monitor treatment response during syphilis infection. Syphilis- and HIV-coinfected patients may experience incomplete resolution in non-treponemal titres, which is referred to as the serofast state. The goal of this study was to evaluate risk factors for serofast state in HIV-infected patients.

METHODS

From November 2015 to June 2018, 1530 HIV-positive patients were tested for syphilis using a Treponema pallidum particle agglutination (TPPA) assay. Among TPPA-positive patients, medical records were reviewed for early syphilis infection. Serofast state was defined as a less than four-fold decrease in non-treponemal antibody titres during a 6-month follow-up period in the absence of symptoms of syphilis. Baseline characteristics were tested as predictive factors of serological response.

RESULTS

In all, 515 patients (33.7%) tested positive in TPPA assays, and in 163 patients at least one previous syphilis infection was documented. A total of 61 out of 163 patients (37.4%) were in a serofast state. A history of previous syphilis infection (61 vs. 43%; P = 0.04) was more common in serofast patients than in patients with serological cure after 6 months. Non-treponemal titres ≥ 1:32 before therapy (47 vs. 25%; P = 0.005) and adjunctive corticosteroids to prevent the Jarisch-Herxheimer reaction (35% vs 15%; P = 0.006) were associated with serological cure after 6 months, but corticosteroid therapy had no influence at 12 months. The intensity of syphilis treatment did not affect serological cure.

CONCLUSION

Corticosteroids for prevention of the Jarisch-Herxheimer reaction were associated with earlier serological cure. Although serological response is the accredited surrogate method to monitor syphilis treatment, the biological significance of the serofast state remains unclear.

Recurrent ocular syphilis in a patient living with HIV

A 26-year-old male living with human immunodeficiency virus (HIV) and who had previously been treated for ocular syphilis presented to the Emergency Department with progressive vision loss and uveitis. The efficacy of standard management for neurosyphilis in HIV and recurrence was examined.

Natural experiment of syphilis treatment with doxycycline or benzathine penicillin in HIV-infected patients

BACKGROUND

Although doxycycline is widely used as an alternative to benzathine penicillin for the treatment of early and late latent syphilis, data on serological response following treatment with doxycycline among HIV-infected patients are limited.

METHODS

In this study, we analysed serological response to syphilis treatment with doxycycline among HIV-infected patients treated during a benzathine penicillin shortage period and compared with treatment response among patients treated with benzathine penicillin. Cases with neurosyphilis and those treated with suboptimal doses or with concurrent medications in association with benzathine penicillin or doxycycline were excluded.

RESULTS

Fifty patients treated with doxycycline from September 2014 to December 2016 were compared with 115 patients treated with benzathine penicillin for early, late latent or latent syphilis of unknown duration. Patients treated with doxycycline were slightly older [(median 49 years old, 95% confidence interval (95% CI) 43-56] than those in the penicillin group (median 44 years old, 95% CI 37-50; P = 0.007). Groups had no statistically significant differences regarding sex, HIV suppression under treatment and syphilis stages. Serological response to treatment, defined as a nonreagent Venereal Disease Research Laboratory (VDRL) or at least a four-fold reduction in VDRL titres measured 6-12 months after treatment, was seen in 72% (95% CI 58-84) of patients treated with doxycycline and 70% (95% CI 60-78) of patients treated with penicillin (P = 0.753).

CONCLUSION

We found no statistically significant differences in serological response to treatment with doxycycline or benzathine penicillin among HIV-infected patients with early, late latent or latent syphilis of unknown duration. Our findings suggest that doxycycline is an acceptable treatment to HIV-infected patients with nontertiary stages of syphilis.