Role of IgM testing in the diagnosis and post-treatment follow-up of syphilis: a prospective cohort study

Persistence of Treponema pallidum IgM antibodies in serum: What is their meaning?

We studied the detection of Treponema pallidum (TP)-IgM antibodies in the serum of 69 patients treated for syphilis. The persistence of TP-IgM antibodies in serum for more than 3 years was the only clue to suspect an active infection and, therefore, to investigate a central nervous system involvement.

Advantages and limitations of current diagnostic laboratory approaches in syphilis and congenital syphilis

INTRODUCTION

The reemergence of syphilis, especially congenital syphilis, presents a significant public health threat. Accurate diagnosis of syphilis depends on recognition of a constellation of symptoms, review of medical and sexual history, and multiple laboratory tests. While reliable, current tests for syphilis can be difficult to interpret, which can lead to delays in treatment.

AREA COVERED

This review summarizes the major advantages and limitations of available diagnostic laboratory methods for syphilis, provides an update on recent advances in laboratory tools, and highlights the urgent need for coordinated efforts to create new tools to halt the resurgence of syphilis.

EXPERT OPINION

In syphilis, the wide variety of short-lived signs and symptoms followed by periods of latency create diagnostic challenges. Currently available laboratory tests, when positive, require additional information to interpret (prior testing, treatment, and sexual history). Point-of-care tests that can rapidly and accurately detect both treponemal and non-treponemal antibodies would be a huge step toward reducing test turnaround time and time to treatment. Incorporating biological insights and technology innovations to advance the development of direct detection assays is urgently needed. A comprehensive coordinated effort is critical to stem the tide of rising syphilis in the United States and globally.

Evaluation of the nontreponemal IgM antibodies in syphilis serofast patients: A new serologic marker for active syphilis

BACKGROUND

Serofast status is challenging to interpret in clinical work, and distinguishing active syphilis in serofast patients can provide a reference for clinical diagnosis and treatment. However, effective serologic markers for active syphilis are still lacking.

OBJECTIVES

We aimed to explore the possibility of nontreponemal IgM antibodies in distinguishing active syphilis in serofast patients.

METHODS

A total of 1501 clinical serum samples were collected from 301 serofast patients, and nontreponemal IgM antibodies were detected by chemiluminescence immunoassay.

RESULTS

The results showed that a total of 29 samples (9.63%) of 301 serofast patients were positive for nontreponemal IgM antibodies, and our limited follow-up data showed that 66.67% (2/3) of the serofast patients progressed to neurosyphilis and cardiovascular syphilis.

CONCLUSION

These findings demonstrate that most serofast patients with positive nontreponemal IgM antibodies have evidence of progressive syphilis, and nontreponemal IgM antibodies can be used as a new serologic marker for the activity of syphilis. Nontreponemal IgM antibodies may play a role in the management of serofast patients.

Duration of anti-treponemal immunoglobulin M seroreversion after successful syphilis treatment in HIV-positive and -negative patients

Treponemal immunoglobulin M (IgM) antibody detection is currently among serologic tests used for syphilis diagnosis. However, the exact role of these antibodies is unclear. In this retrospective study of 326 (198 HIV positive and 128 negative) patients with early syphilis and positive IgM serology, data were analysed to investigate the time of IgM seroreversion after treatment and correlation with covariate factors. Median time of IgM seroreversion in the study population was 9 months (range 3-84, interquartile range 5-12). No statistically significant difference was observed between HIV-positive and -negative patients. At 12 months, 80.1% of the patients had a negative IgM test. At 6 months, 100% of HIV-positive patients had a fourfold decrease or greater in Venereal Disease Research Laboratory titres, but only 35.4% had a negative treponemal IgM. Secondary and early latent stage patients had a slower seroreversion of IgM (Hazard Ratio (HR) = 0.73, p = 0.064 and HR = 0.60, p = 0.023, respectively) than those with primary syphilis. A very strong association was observed of time to seroreversion of treponemal IgM with baseline VDRL titre (p < 0.001). Treponemal IgM antibody detection often cannot distinguish between active and successfully treated syphilis. Treponemal IgM may only be useful in the cases recommended in the guidelines, and in cases of untreated syphilis, it could support but not confirm the diagnosis.