Single Dose Versus 3 Doses of Intramuscular Benzathine Penicillin for Early Syphilis in HIV: A Randomized Clinical Trial

BASHH UK guidelines for the management of syphilis 2024

The 2024 UK guidelines for the management of syphilis are in line with current evidence and practice within the UK. Key updates are detailed at the start of the article. These guidelines are accompanied by the first UK guidelines for the management of syphilis in pregnant people and children, 2024.

Treatment of bacterial sexually transmitted infections in Europe: gonorrhoea, Mycoplasma genitalium, and syphilis

This review explores the therapeutic challenges of sexually transmitted infections (STI) in Europe, which include increasing antimicrobial resistance and limited progress in drug discovery. We primarily focus on gonorrhoea, Mycoplasma genitalium, and syphilis infections. For gonorrhoea with escalating resistance rates we explore the possibility of combining ceftriaxone with another antibiotic or using alternative antibiotics to mitigate resistance emergence, and we provide insights on the ongoing evaluation of new antimicrobials, like gepotidacin and zoliflodacin. In the case of M. genitalium, which exhibits high resistance rates to first and second-line treatments, we emphasize the importance of resistance-guided therapy in regions with elevated resistance levels, and highlight the limited alternative options, such as pristinamycin and minocycline. Furthermore, we address the challenges posed by syphilis, where the primary treatment consists of penicillin or doxycycline, with challenges arising in neurosyphilis, allergy, pregnancy, and supply shortages and discuss the ongoing evaluation of alternative antimicrobials (e.g., ceftriaxone, cefixime, linezolid). Our findings identify priority actions and provide concrete solutions for long-term effective management of STIs and antimicrobial resistance mitigation.

Combination of Amoxicillin 3000 mg and Probenecid Versus 1500 mg Amoxicillin Monotherapy for Treating Syphilis in Patients With Human Immunodeficiency Virus: An Open-Label, Randomized, Controlled, Non-Inferiority Trial

BACKGROUND

Amoxicillin plus probenecid is an alternative to intramuscular benzathine penicillin G for treating syphilis in the United Kingdom. Low-dose amoxicillin is an alternative treatment option used in Japan.

METHODS

We conducted an open-label, randomized, controlled, non-inferiority trial between 31 August 2018, and 3 February 2022, to compare 1500 mg low-dose amoxicillin monotherapy with the combination of 3000 mg amoxicillin and probenecid (non-inferiority margin 10%). Patients with human immunodeficiency virus (HIV) infection and syphilis were eligible. The primary outcome was the cumulative serological cure rate within 12 months post-treatment, measured using the manual rapid plasma reagin card test. Secondary outcomes included safety assessment.

RESULTS

A total of 112 participants were randomized into 2 groups. Serological cure rates within 12 months were 90.6% and 94.4% with the low-dose amoxicillin and combination regimens, respectively. Serological cure rates for early syphilis within 12 months were 93.5% and 97.9% with the low-dose amoxicillin and combination regimens, respectively. Non-inferiority of low-dose amoxicillin compared with amoxicillin plus probenecid overall and for early syphilis was not confirmed. No significant side effects were detected.

CONCLUSIONS

This is the first randomized controlled trial to demonstrate a high efficacy of amoxicillin-based regimens for treating syphilis in patients with HIV infection, and the non-inferiority of low-dose amoxicillin compared with amoxicillin plus probenecid was not seen. Therefore, amoxicillin monotherapy could be a good alternative to intramuscular benzathine penicillin G with fewer side effects. However, further studies comparing with benzathine penicillin G in different populations and with larger sample sizes are needed.

TRIALS REGISTRATION

(UMIN000033986).

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.

Diagnosis and treatment of syphilis: 2019 Belgian National guideline for primary care

OBJECTIVES

In the last 10 years, Belgium and countries of the European Economic Area and other high-income countries observed an increasing trend in syphilis diagnoses. Men who have sex with men (MSM) are the most affected population explained by high rates of unprotected sex, a greater number of sexual partners, and risk compensation as a result of pre-exposure prophylaxis use. The 2019 European Centre for Disease Prevention and Control (ECDC) technical report on syphilis proposed interventions such as enhanced screening of specific populations at risk. This guideline will address these issues.

METHODS

We performed a systematic review of the evidence for diagnosing and treating syphilis.

RESULTS

Based on the results, recommendations were formulated for primary health care professionals in Belgium. This syphilis guideline addresses prioritised testing, the sample and test for the diagnosis, the treatment of a person with syphilis including syphilis serology follow-up, and partner management.

CONCLUSION

The identification and management of patients with syphilis will benefit from the application of this guideline.

A 2021 Update on Syphilis: Taking Stock from Pathogenesis to Vaccines

In 2021 the scientific community's efforts have been focused on solving the back-breaking challenge of the COVID-19 pandemic, but sexually transmitted infections (STI) are still one of the most common global health problems. Syphilis is a systemic disease caused by the spirochaete Treponema pallidum (TP) and is one of the oldest known diseases. Its incidence has increased in the last few years and syphilis still remains a contemporary plague that continues to afflict millions of people worldwide. Despite research improvements, syphilis pathogenesis is not completely clear; clinical presentation is very heterogeneous and the diagnosis can sometimes be difficult. Furthermore, few therapeutic options are available, and a vaccine has not been found yet. In this review, we describe the most recent evidence concerning the clinical manifestation, diagnosis, treatment and vaccine prospectives for this disease.

Comparisons of Serologic Responses of Early Syphilis to Treatment with a Single-Dose Benzathine Penicillin G Between HIV-Positive and HIV-Negative Patients

Introduction

Poorer serologic responses of early syphilis to treatment have been inconsistently reported in HIV-positive patients compared with HIV-negative patients, but the interpretation of previous studies is limited by discrepant study designs. The present study aimed to evaluate the effect of HIV infection on the treatment response to a single dose of benzathine penicillin G (BPG) for early syphilis.

Methods

From January 2015 to March 2020, adult patients with early syphilis who received a single dose of BPG were enrolled and rapid plasma reagin (RPR) titers were periodically determined. The primary outcome was serologic response, defined as at least a fourfold decline of RPR titer at 12 months of BPG treatment compared with that at baseline, which was examined in the intention-to-treat (ITT) and per-protocol analyses. Treatment failure included lack of at least a fourfold decline in RPR titers and at least a fourfold increase in RPR titers.

Results

We prospectively enrolled 184 HIV-positive and 68 HIV-negative participants with early syphilis, who were all men who have sex with men, with a higher proportion of previous syphilis (70.1%) and early latent syphilis (64.1%) among HIV-positive participants. In the ITT with last-observation-carried-forward analysis, HIV-positive participants had a significantly lower serologic response rate at 12 months of treatment than HIV-negative participants (73.4% vs. 91.2%). Of HIV-positive participants, 12.5% failed to achieve at least fourfold decline in RPR titers and 14.1% had at least a fourfold increase in RPR titers. The factors associated with 12-month serologic response were HIV infection (adjusted odds ratio [AOR] 0.33; 95% confidence interval [CI] 0.13–0.81) and RPR titer (per 1-log₂ increase, AOR 1.36; 95% CI 1.23–1.51).

Conclusion

HIV-positive patients with early syphilis had poorer serologic responses to BPG treatment than HIV-negative patients during a 12-month follow-up period.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40121-021-00450-6.

Ocular and neurosyphilis: epidemiology and approach to management

PURPOSE OF REVIEW

In the context of a resurgence of syphilis worldwide, it can be anticipated that a rise in cases of ocular, otic, and neurosyphilis will also be seen. This article reviews the current epidemiology, manifestations, and approach to management and treatment.

RECENT FINDINGS

Although studies continue investigating alternate approaches and new diagnostic tests for ocular and neurosyphilis, few data exist to change current diagnostic algorithms and approaches to diagnosis, management, or follow up.

SUMMARY

The diagnosis of neurologic and eye/ear involvement with syphilis may be delayed because of a lack of specificity of findings, low suspicion for syphilis, fluctuation in symptoms, and/or similarities in presentation to other diseases. A high index of suspicion for syphilis and re-education about the protean manifestations of syphilis by all clinicians is required provide timely diagnosis and management of ocular, otic, and neurosyphilis.

Deciphering the serological response to syphilis treatment in men living with HIV

OBJECTIVE

To examine syphilis serology after treatment in people living with HIV. No unanimous guidelines exist in the era of increasing coinfection.

DESIGN

Retrospective review using a tertiary care clinic in Toronto from 2000 to 2017.

METHODS

The 2015 Centers for Diseases Control and Prevention syphilis guidelines were used to define an adequate serologic response. Cumulative distribution estimates and proportional hazards models accounting for interval censoring estimated the time to serologic response and seroreversion. Multistate models were used to investigate extended periods of serofast serology.

RESULTS

A total of 171 patients with syphilis met our inclusion criteria (16 primary, 53 secondary, 26 early latent, 46 late latent, 30 neurosyphilis). Serologic response was achieved by 12 months for 65 (94%) patients and by 12-18 months for four (6%) patients with primary/secondary syphilis. For latent and neurosyphilis, 94 (92%) achieved serologic response by 24 months and one (1%) at 24.1 months. 84 (49%) patients achieved seroreversion with a median (95% confidence interval) time of 2 (1.44, 2.68) years. Latent syphilis was associated with a lower likelihood of achieving serologic response [hazard ratio (HR) = 0.52, P = 0.05] and seroreversion (HR = 0.27, P < 0.001) compared with primary/secondary syphilis. The probability of moving from a new infection state to a serofast state within 1 year was high (0.65) but the 1-year probability of transitioning from a serofast state to seroreversion was low (0.27).

CONCLUSION

The majority of people living with HIV infected with syphilis will achieve an adequate serologic response as per the Centers for Diseases Control and Prevention guidelines. Seroreversion was observed in about half but can take years to occur.

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.

Neuroborreliosis and Neurosyphilis

PURPOSE OF REVIEW

This article presents an overview of the current diagnosis and management of two spirochetal infections of the nervous system, neuroborreliosis (Lyme disease) and neurosyphilis, focusing on similarities and differences. Although neuroborreliosis was first identified almost a century ago, much confusion remains about how to accurately diagnose this quite treatable nervous system infection. Well-established diagnostic tools and therapeutic regimens exist for neurosyphilis, which has been well-known for centuries.

RECENT FINDINGS

Serologic testing targeting the C6 antigen may simplify diagnostic testing in neuroborreliosis while improving accuracy. Historically, screening for syphilis has used a reaginic test followed by a treponeme-specific assay; alternative approaches, including use of well-defined recombinant antigens, may improve sensitivity without sacrificing specificity. In neuroborreliosis, measurement of the chemokine CXCL13 in CSF may provide a useful marker of disease activity in the central nervous system.

SUMMARY

Lyme disease causes meningitis, cranial neuritis, radiculitis, and mononeuropathy multiplex. Cognitive symptoms, occurring either during (encephalopathy) or after infection (posttreatment Lyme disease syndrome) are rarely, if ever, due to central nervous system infection. Posttreatment Lyme disease syndrome is not antibiotic responsive. Syphilis causes meningitis, cranial neuritis, chronic meningovascular syphilis, tabes dorsalis, and parenchymal neurosyphilis. The organism remains highly sensitive to penicillin, but residua of chronic infection may be irreversible.

Incidence and Predictors of Serological Treatment Response in Early and Late Syphilis Among People Living With HIV

Background

Few studies have investigated predictors of serological response to syphilis treatment in people living with HIV (PLWH).

Methods

This was a retrospective, longitudinal study on PLWH who were diagnosed with and treated for syphilis who had an assessable serological response between January 2004 and June 2016. Serological treatment response (TR) was defined as a ≥4-fold decline in rapid plasma reagin (RPR) titers or a reversion to nonreactive (if RPR ≤1:4 at diagnosis) 12 months after treatment for early syphilis and 24 months after treatment for late syphilis. Factors associated with a TR were assessed with multivariate Cox proportional hazard models for recurrent events.

Results

A total of 829 episodes of syphilis (686 early, 143 late) in 564 patients were recorded. TR was observed in 732 (88%) syphilis episodes. The proportion of TR differed between early and late syphilis (89% vs 83%, respectively; P = .045). For early syphilis, TR was associated with a higher nadir CD4+ cell count (adjusted hazard ratio [AHR], 1.06; P = .029), an RPR titer >1:32 at diagnosis (AHR, 1.26; P = .009), secondary syphilis (AHR, 1.29; P = .008), and cases of syphilis diagnosed in more recent calendar years (AHR, 1.36; P < .0001). In late syphilis, TR was more likely to occur for first infections (AHR, 1.80; P = .027), for episodes that occurred in more recent years (AHR, 1.62; P = .007), and for RPR titers >1:32 at diagnosis (AHR, 2.04; P = .002). TR was not associated with the type of treatment regimen in early and late syphilis.

Conclusions

Higher RPR titers at diagnosis and a diagnosis of syphilis that was made in more recent years were associated with TR in early and late syphilis.