Clinical factors associated with syphilis concordance in men in sexual partnerships: a cross-sectional couples study

Developing a symptoms-based risk score for infectious syphilis among men who have sex with men

Background

Syphilis incidence is rising among men who have sex with men (MSM). An online tool based on a risk score identifying men with higher risk of infectious syphilis could motivate MSM to seek care. We aimed therefore to develop a symptoms-based risk score for infectious syphilis.

Methods

We included data from all consultations by MSM attending the Amsterdam Centre for Sexual Health in 2018–2019. Infectious syphilis (ie, primary, secondary or early latent syphilis) was diagnosed according to the centre’s routine protocol. Associations between symptoms and infectious syphilis were expressed as odds ratios (OR), with 95% confidence intervals (CI). Based on multivariable logistic regression models, we created risk scores, combining various symptoms. We assessed the area under the curve (AUC) and cut-off based on the Youden Index. We estimated which percentage of MSM should be tested based on a positive risk score and which percentage of infectious syphilis cases would then be missed.

Results

We included 21,646 consultations with 11,594 unique persons. The median age was 34 years (IQR 27–45), and 14% were HIV positive (93% on antiretroviral treatment). We diagnosed 538 cases of infectious syphilis. Associations with syphilis symptoms/signs were strong and highly significant, for example, OR for a painless penile ulcer was 35.0 (CI 24.9 to 49.2) and OR for non-itching rash 57.8 (CI 36.8 to 90.9). Yet, none of the individual symptoms or signs had an AUC >0.55. The AUC of risk scores combining various symptoms varied from 0.68 to 0.69. For all risk scores using cut-offs based on Youden Index, syphilis screening would be recommended in 6% of MSM, and 59% of infectious syphilis cases would be missed.

Conclusion

Symptoms-based risk scores for infectious syphilis perform poorly and cannot be recommended to select MSM for syphilis screening. All MSM with relevant sexual exposure should be regularly tested for syphilis.

Infection Risk in Sexual Contacts of Syphilis: A Systematic Review and Meta-analysis

OBJECTIVES

Current guidelines recommend offering epidemiological treatment to asymptomatic contacts of early syphilis. This is on the expectation that up to 60% of sexual contacts of patients with syphilis will be infected. However, the evidence for this figure is sparse. We performed a systematic review and meta-analysis, to estimate the proportion of sexual contacts of syphilis that are infected with syphilis.

METHODS

Two electronic databases (Medline and Embase) were reviewed in March 2021, to identify studies that reported rates of infection in sexual contacts of syphilis.

RESULTS

Of 3,051 Embase and 1,828 Medline articles identified, 32 were included in the meta-analysis. In total 36,397 contacts were tested. The proportion of contacts infected varied across the studies, ranging from 10.7% to 97.5%, resulting in considerable heterogeneity (I²=98.5%). Pooling the studies gave an estimated proportion of infected contacts of 32.6% (95% confidence interval: 26.2% - 39.7%).

CONCLUSIONS

The risk of infection in sexual contacts of syphilis reported in the literature is highly variable, with a pooled estimate of 32.6%. This will help guide decisions regarding epidemiological treatment of sexual contacts of patients with syphilis. These decisions are increasingly important in this era of antibiotic resistance, with increasing emphasis being placed on antimicrobial stewardship.

Syphilis, HIV and other STI positivity in clients presenting as contacts of syphilis at Sydney Sexual Health Centre

There is a paucity of contemporary data pertaining to sexually transmitted infection test positivity of people presenting as contacts of syphilis. Over a 12 month period in 2018, within a sexual health service, we identified 191 (92% men who have sex with men) presentations, 7.8% were diagnosed with syphilis (three primary, four secondary, six early latent and two late latent infections). A total of 20.8% (38/183) were diagnosed with one or more STI including 54 non-syphilis infections: two (1.1%) new HIV; 26 (14.2%) Chlamydia trachomatis; and 24 (13.1%) Neisseria gonorrhoeae. Although syphilis test positivity in contacts is low, this population requires comprehensive STI screening and HIV prevention discussion.

Clinical Presentation of Incident Syphilis Among Men Who Have Sex with Men Taking HIV Pre-Exposure Prophylaxis in Melbourne, Australia

BACKGROUND

Current international guidelines on human immunodeficieny virus (HIV) Pre-Exposure Prophylaxis (PrEP) recommend serological screening for syphilis at routine 3-monthly PrEP appointments. The aim of our study was to describe the pattern of clinical presentation of syphilis among men who have sex with men (MSM) taking PrEP. We were interested in whether syphilis is detected through screening at scheduled3-monthly PrEP clinic appointments or whether primary or secondary syphilis presented at unscheduled interval visits.

METHODS

This was a retrospective study of MSM attending the PrEP clinic at the Melbourne Sexual Health Centre between February 2016 and March 2019. Serological screening for syphilis was routinely undertaken at 3-monthly PrEP clinic appointments. Diagnoses of early syphilis were identified from PrEP clinic visits and from interim walk-in STI clinic attendances.

RESULTS

There were 69 cases of early syphilis among 61 MSM taking PrEP during the study period. There were 24 (35%) primary, 16 (23%) secondary, and 29 (42%) early latent infections. The incidence of early syphilis was 8.6 per 100 person-years. A substantial proportion of primary (58%) and secondary (44%) syphilis diagnoses were made at interim STI clinic attendances, between PrEP appointments.

CONCLUSIONS

Syphilis screening at routine 3-monthly PrEP visits alone fails to detect a proportion of primary and secondary syphilis infections and may be insufficient in preventing onward transmission. Education of MSM taking PrEP regarding the risk of syphilis and symptom recognition is necessary together with access to syphilis testing between PrEP visits.

Treponema pallidum detection in lesion and non-lesion sites in men who have sex with men with early syphilis: a prospective, cross-sectional study

BACKGROUND

Syphilis transmission is increasing, and precisely how Treponema pallidum is transmitted sexually from person to person is unclear. We aimed to determine the frequency of T pallidum shedding from potentially asymptomatic sites and the stage of infection at which shedding is most frequent in men who have sex with men (MSM), who have been disproportionately affected by syphilis.

METHODS

We did a prospective, cross-sectional study in MSM recruited from Melbourne Sexual Health Centre (Melbourne, VIC, Australia). Men were eligible if they were aged 18 years or older, reported sex with men during the past 12 months, and had laboratory confirmed primary, secondary, or early latent syphilis, consistent with Australian definitions. Primary and secondary syphilis lesions were swabbed and non-lesion samples were collected via oral rinse, oral cavity swab, anal canal swab, urine, and semen. Samples were tested for T pallidum using PCR assays targeting polA (lesion and non-lesion samples) and 47 kDa (non-lesion samples only) gene targets. The primary outcome was the proportion of men with T pallidum detected from potentially asymptomatic sites-namely, the mouth, anus, urethra, and semen.

FINDINGS

Between Nov 30, 2015, and May 23, 2019, 246 MSM were screened for inclusion, of whom 200 had serologically confirmed early syphilis and were included in the study: 54 (27%) of 200 had primary syphilis, 93 (47%) had secondary syphilis, and 53 (27%) had early latent syphilis. T pallidum DNA was detected in 48 (24%; 95% CI 18·3-30·5) of 200 men by oral rinse or oral lesion swab, or both, of whom 24 had no oral lesions. Oral T pallidum detection was most frequent in those with secondary syphilis compared with those at other stages of disease (41 [44%] of 93 vs seven [7%] of 107; p<0·0001), and in men with rapid plasma reagin titres of 1/64 or higher compared with those with lower titres (37 [32%] of 117 vs 11 [13%] of 83; p=0·0026). T pallidum was detected by anal canal swab or anal lesion swab, or both, in 45 (23·0%; 95% CI 17·3-29·5) of 196 men with available samples, of whom ten had no anal lesion. Furthermore, T pallidum was detected in urine samples of 12 (6·1%, 3·2-10·3) of 198 men and in semen samples from six (12·0%, 4·5-24·3) of 50 men who provided samples. Among the 93 men with secondary syphilis, 69 (74%) had T pallidum detected at any site, and 24 (26%) had detection at two or more separate sites. Among the 54 men with primary syphilis, 49 (91%) had T pallidum detected at any site, and 11 (20%) had detection at two or more separate sites. Among the 53 men with early latent syphilis, four (8%) had T pallidum detected at any site and none had T pallidum detected at two or more separate sites.

INTERPRETATION

Unrecognised oral and anal shedding of T pallidum occurs in MSM with early syphilis, most frequently in those with secondary syphilis, suggesting secondary syphilis is the most infectious stage and that earlier detection and treatment of syphilis to prevent progression to the secondary stage might improve syphilis control. Future research is needed to ascertain the contribution of shedding of T pallidum from non-lesion sites to transmission of syphilis.

FUNDING

Australian National Health and Medical Research Council.

Timing of primary syphilis treatment and impact on the development of treponemal antibodies: a cross-sectional clinic-based study

BACKGROUND

Serology is negative in a proportion of primary syphilis cases where Treponema pallidum PCR testing is positive. We aimed to identify discordant, T. pallidum PCR-positive, serology-negative primary syphilis cases and any clinical or laboratory factors associated with failure to subsequently seroconvert.

METHODS

Serodiscordant primary syphilis cases that were T. pallidum PCR-positive and serology-negative (including rapid plasma reagin, T. pallidum particle agglutination, T. pallidum enzyme immunoassay or T. pallidum chemiluminescence assay) were identified from the Melbourne Sexual Health Centre electronic records between April 2011 and December 2019. Clinical and laboratory associations were examined.

RESULTS

There were 814 primary syphilis cases in the study period and 38 (4.7%) were serodiscordant, 35 in men who have sex with men. Thirty-two had follow-up serology performed a median of 24 days later, of which 16 (50%) seroconverted, mostly (81%) within 6 weeks. Failure to seroconvert was significantly associated with treatment on day 1. Of the 12 cases treated on day 1, 10 (83%) failed to seroconvert compared with 6 of 20 (30%) among those who were treated after day 1.

DISCUSSION

Earlier treatment of primary syphilis can prevent the development of serological markers. T. pallidum PCR can identify primary syphilis lesions before the development of serological markers and improve diagnosis of early primary syphilis lesions. Serology alone will miss a proportion of primary syphilis infections and should be repeated if a diagnosis of syphilis is being considered.

Differences in maternal characteristics and pregnancy outcomes between syphilitic women with and without partner coinfection

BACKGROUND

Partner infection is a significant factor in preventing mother-to-child syphilis transmission. We compared pregnancy outcomes between syphilis discordant and syphilis concordant couples.

METHODS

We conducted a retrospective study among 3076 syphilis-positive women who received syphilis screening together with their partners during pregnancy. Multivariate analysis was used to explore risks for abnormal outcomes in objects correcting for the major covariate factors. Adjusted odds ratios (OR) and 95% confidence intervals (CI) were estimated to compare pregnancy outcomes between syphilis concordant and syphilis discordant couples.

RESULTS

Overall, 657 of the 3076 women were diagnosed with gestational syphilis and had a syphilis-positive partner, giving a partner concordance prevalence of 21.36%. Women in concordant couples were more likely to have higher parity, more children, late antenatal care and syphilis screening, a lower proportion of latent syphilis, and elevated serologic titers than women in discordant couples (P < 0.01 for all). Totally, 10.08% of women had adverse pregnancy outcomes. Multivariate analysis showed partners' syphilis infection (OR_adj = 1.44, 95% CI: 1.10-1.89), untreated pregnancy syphilis (OR_adj = 1.67, 95% CI: 1.15-2.43), and higher maternal serum titers (> 1:8) (OR_adj = 1.53, 95% CI: 1.17-2.00) increased the risks of adverse pregnancy outcomes. Concordance was associated with increased risk for stillbirth (OR_adj = 2.86, 95%CI:1.36-6.00), preterm birth (PTB) (OR_adj = 1.38,95%CI:1.02-1.87) and low birth weight (LBW) (OR_adj = 1.55, 95%CI:1.13-2.11) compared with discordance. Even among treated women, concordance was associated with increased risk for stillbirth (OR_adj = 3.26, 95%CI:1.45-7.31) and LBW (OR_adj = 1.52, 95%CI:1.08-2.14). Among women with one treatment course, the risks for PTB(OR_adj = 1.81, 95%CI:1.14-2.88) and LBW(OR_adj = 2.08, 95%CI:1.28-3.38)were also higher among concordant couples than discordant couples. Nevertheless, there were no significant differences between concordant and discordant couples in risks of stillbirth (OR_adj = 2.64, 95% CI: 0.98-7.05),PTB (OR_adj = 1.15, 95% CI: 0.76-1.74), and LBW(OR_adj = 1.21, 95% CI: 0.78-2.02) among women with two treatment courses.

CONCLUSION

Male partner coinfection increased the risks for stillbirth, PTB and LBW, particularly when gestational syphilis treatment was suboptimal. However, this risk could be reduced by adequate treatment.