Rising rates of syphilis in the era of syphilis elimination

Syphilis in Hematopathology Practice: A Diagnostic Challenge

CONTEXT.—

Syphilis, a reemerging disease caused by the spirochete Treponema pallidum, is becoming more frequent in surgical pathology and hematopathology practices. Hematopathologists typically receive lymph node biopsies from patients with syphilis who have localized or diffuse lymphadenopathy. Occasionally, syphilis infection in the aerodigestive tract can show a prominent lymphoplasmacytic infiltrate and mimic lymphoma. Besides the varying and occasional atypical morphology, the fact that clinical suspicion tends to be low or absent when histologic evaluation is requested adds to the importance of making this diagnosis.

OBJECTIVE.—

To summarize histologic features of syphilitic lymphadenitis and syphilis lesions in the aerodigestive tract, and to review differential diagnosis and potential diagnostic pitfalls.

DATA SOURCES.—

Literature review via PubMed search.

CONCLUSIONS.—

Characteristic histologic findings in syphilitic lymphadenitis include thickened capsule with plasma cell-rich inflammatory infiltrate, reactive follicular and paracortical hyperplasia with prominent lymphoplasmacytic infiltrate, and vasculitis. Lymph nodes, however, can show a number of other nonspecific histologic features, which frequently makes the diagnosis quite challenging. In the aerodigestive tract, syphilis is characterized by plasma cell-rich infiltrates. Immunohistochemistry for T pallidum is the preferred method for detecting spirochetes; however, this immunohistochemical stain shows cross-reactivity with other treponemal and commensal spirochetes. Differential diagnosis of syphilis in lymph nodes and the aerodigestive tract is broad and includes reactive, infectious, and neoplastic entities. Pathologists should be aware of the histologic features of syphilis and keep this challenging entity in the differential diagnosis.

Previous Sexually Transmitted Infections and Partner Services Interviews as Predictors of Subsequent Interview Completion Among Cisgender MSM: Partner Services Fatigue?

BACKGROUND

Anecdotal reports suggest that partner services (PS) are less successful among people with repeat sexually transmitted infection (STI) diagnoses and/or previous PS interactions. We examine whether having repeated STI diagnoses and/or PS interactions is associated with PS outcomes among men who have sex with men (MSM).

METHODS

With STI surveillance and PS data for MSM diagnosed with gonorrhea, chlamydia, and/or syphilis from 2007 to 2018, in King County, WA, we used Poisson regression models to examine the relationships between PS outcomes (e.g., completing a PS interview and providing identifying information for a contact) with (1) number of previous STI case episodes and (2) number of previous PS interviews completed.

RESULTS

Of the 18,501 MSM STI case patients initiated for interview in the analytic period (2011-2018), 13,232 (72%) completed a PS interview, and 8,030 (43%) had at least 1 prior PS interview. The proportion of initiated cases successfully interviewed declined from 71% among those with no previous PS interview to 66% among those with ≥3 prior interviews. Similarly, the proportion of interviews with ≥1 partner identified declined with greater numbers of previous PS interviews (from 46% [0 interviews] to 35% [≥3 interviews]). In multivariate models, having ≥1 prior PS interview was negatively associated with completing a subsequent interview and providing partner locating information.

CONCLUSIONS

Having a history of STI PS interviews is associated with less PS engagement among MSM. New approaches to PS should be explored to address the growing epidemic of STIs among MSM.

Interest, Concerns, and Attitudes Among Men Who Have Sex With Men and Health Care Providers Toward Prophylactic Use of Doxycycline Against Chlamydia trachomatis Infections and Syphilis

BACKGROUND

Prophylactic administration of doxycycline is regarded as a potential new public health strategy to combat the rising rates of Chlamydia trachomatis infections and syphilis among men who have sex with men. We conducted a survey-based study to evaluate how community members and health care providers in Southern California would perceive doxycycline preexposure/postexposure prophylaxis (PrEP/PEP) to predict its acceptability and identify potential areas of concern.

METHODS

We conducted an online cross-sectional survey among community members who identify as men who have sex with men and health care providers with prescribing authority in Southern California to investigate the current attitudes toward doxycycline PrEP/PEP, including their willingness to accept. We analyzed the data using descriptive statistics and binary logistic regression.

RESULTS

Among 212 enrolled community member participants, 67.5% indicated they would take doxycycline PrEP/PEP if offered by their provider. Higher acceptability was significantly associated with several characteristics, including recent history of bacterial sexually transmitted infection diagnosis and current use of HIV PrEP. For health care providers, 89.5% of 76 enrolled participants expressed willingness to prescribe doxycycline PrEP/PEP to their patients if recommended by the Centers for Disease Control and Prevention, but only 43.4% were willing if not. Both community members and health care providers demonstrated high levels of concern toward possible drug resistance.

CONCLUSIONS

Doxycycline PrEP/PEP as a preventive strategy against chlamydial infections and syphilis would likely be accepted among community members and health care providers. Clear guidelines from public health officials and further clarification on the strategy's potential impact on developing drug resistance may be necessary to ensure successful implementation.

Biophysical and Biochemical Characterization of TP0037, a d-Lactate Dehydrogenase, Supports an Acetogenic Energy Conservation Pathway in Treponema pallidum

A longstanding conundrum in Treponema pallidum biology concerns how the spirochete generates sufficient energy to fulfill its complex pathogenesis processes during human syphilitic infection. For decades, it has been assumed that the bacterium relies solely on glucose catabolism (via glycolysis) for generation of its ATP. However, the organism's robust motility, believed to be essential for human tissue invasion and dissemination, would require abundant ATP likely not provided by the parsimony of glycolysis. As such, additional ATP generation, either via a chemiosmotic gradient, substrate-level phosphorylation, or both, likely exists in T. pallidum Along these lines, we have hypothesized that T. pallidum exploits an acetogenic energy conservation pathway that relies on the redox chemistry of flavins. Central to this hypothesis is the apparent existence in T. pallidum of an acetogenic pathway for the conversion of d-lactate to acetate. Herein we have characterized the structural, biophysical, and biochemical properties of the first enzyme (d-lactate dehydrogenase [d-LDH]; TP0037) predicted in this pathway. Binding and enzymatic studies showed that recombinant TP0037 consumed d-lactate and NAD+ to produce pyruvate and NADH. The crystal structure of TP0037 revealed a fold similar to that of other d-acid dehydrogenases; residues in the cofactor-binding and active sites were homologous to those of other known d-LDHs. The crystal structure and solution biophysical experiments revealed the protein's propensity to dimerize, akin to other d-LDHs. This study is the first to elucidate the enzymatic properties of T. pallidum's d-LDH, thereby providing new compelling evidence for a flavin-dependent acetogenic energy conservation (ATP-generating) pathway in T. pallidumIMPORTANCE Because T. pallidum lacks a Krebs cycle and the capability for oxidative phosphorylation, historically it has been difficult to reconcile how the syphilis spirochete generates sufficient ATP to fulfill its energy needs, particularly for its robust motility, solely from glycolysis. We have postulated the existence in T. pallidum of a flavin-dependent acetogenic energy conservation pathway that would generate additional ATP for T. pallidum bioenergetics. In the proposed acetogenic pathway, first d-lactate would be converted to pyruvate. Pyruvate would then be metabolized to acetate in three additional steps, with ATP being generated via substrate-level phosphorylation. This study provides structural, biochemical, and biophysical evidence for the first T. pallidum enzyme in the pathway (TP0037; d-lactate dehydrogenase) requisite for the conversion of d-lactate to pyruvate. The findings represent the first experimental evidence to support a role for an acetogenic energy conservation pathway that would contribute to nonglycolytic ATP production in T. pallidum.

Syphilis Elimination: Lessons Learned Again

It is estimated that approximately 20 million new sexually transmitted infections (STIs) occur each year in the United States. The federally funded sexually transmitted disease prevention program implemented by Centers for Disease Control and Prevention is primarily focused on the prevention and control of the three most common bacterial STIs: syphilis, gonorrhea, and chlamydia. A range of factors facilitate the transmission and acquisition of STIs, including syphilis. In 1999, Centers for Disease Control and Prevention launched the National Campaign to Eliminate Syphilis from the United States. The strategies were familiar to public health in general and to sexually transmitted disease control in particular: (1) enhanced surveillance, (2) expanded clinical and laboratory services, ((3) enhanced health promotion, (4) strengthened community involvement and partnerships, and (5) rapid outbreak response. This national commitment to syphilis elimination was not the first effort, and like others before it too did not succeed. However, the lessons learned from this most recent campaign can inform the way forward to a more comprehensive approach to the prevention and control of STIs and improvement in the nation's health.

Differences in Partner Services Outcomes for Men Who Have Sex With Men Diagnosed With Primary and Secondary Syphilis by HIV Serostatus

BACKGROUND

Differences in partner services outcomes in men who have sex with men (MSM) by HIV serostatus have not been explored as a potential driver of differential early syphilis (ES) burden in this population.

METHODS

We compared partner services outcomes (number of partners named, notified, tested, diagnosed, and treated) between HIV-positive and HIV-negative MSM initiated for ES partner services in Texas from 2013 to 2016 using logistic regression and Wilcoxon-Mann-Whitney tests. Logistic regression was used to assess the relationship between HIV serostatus and having a no-partner-initiated (NPI) partner services interview controlling for demographic characteristics, prior partner services interactions, and geosocial phone application use.

RESULTS

A total of 4161 HIV-positive MSM and 5254 HIV-negative MSM were initiated for ES partner services. HIV-positive MSM named fewer partners than did HIV-negative MSM (mean, 1.2 vs. 1.9; P < 0.001) and had lower indices of partners notified, tested, diagnosed, and treated. HIV seropositivity was significantly associated with NPI. However, this association was not significant when limited to MSM with previous partner services interviews (adjusted risk ratio [aRR] 1.06; P = 0.38); in this subset of MSM, using geosocial phone application was negatively associated with having an NPI interview (aRR, 0.90), and having 1 (aRR, 1.33) or more than 1 previous NPI interview (aRR, 1.57) was associated with an NPI interview during the study period.

CONCLUSIONS

Suboptimal outcomes for syphilis partner service may result in missed opportunities for testing and treatment of sexual contacts, which could allow for propagation of syphilis. Implementation of innovative protocols is needed to ensure that partner services continue to be an effective and acceptable method of syphilis disease intervention in MSM.

Déjà vu? A Comparison of Syphilis Outbreaks in Houston, Texas

BACKGROUND

After reaching an all-time low in 2000, syphilis incidence in the United States has increased as the burden shifted from heterosexuals to men who have sex with men (MSM). Houston, Texas, experienced 2 outbreaks of syphilis during this transformation in trends. Further evaluation is necessary to determine if these outbreaks occurred among the same subpopulations.

METHODS

Surveillance data collected on all reported infectious syphilis cases in Houston from 1971 to 2013 were analyzed. Trends in incidence among MSM and human immunodeficiency virus-positive Houston residents were examined. Peak syphilis years subsequent to 1999, years 2007 and 2012, were compared to determine if outbreaks arose in distinctive subpopulations. Categorical variables between these years were compared using chi-square and Fisher's exact tests, whereas further associations between the years were evaluated using multivariable logistic regression.

RESULTS

Incidence among MSM was 20.9 to 32.1 times higher than other men from 2005 to 2013. After adjusting for covariates, cases in 2012 were significantly more likely to be Hispanic (adjusted odds ratio [AOR] = 1.61; 95% confidence interval [95% CI], 1.03-2.53), reported meeting partners via the Internet (AOR, 1.74; 95% CI, 1.18-2.58), and engaged in anonymous sex (AOR, 1.92; 95% CI, 1.40-2.63) in comparison to cases in 2007.

CONCLUSIONS

We found marked disparities of syphilis by subpopulation in Houston. Herein, we present evidence that outbreaks have been distinct in a major southern city with a high burden of syphilis.

Factors associated with reinfection of syphilis in reference centers for sexually transmitted infections

OBJECTIVE

We aim to analyze trend of syphilis and factors associated with recurrent episodes of syphilis among adults and adolescents attended in a STI/AIDS reference centers in Campinas, state of São Paulo, 2004 to 2012.

METHODS

Medical records, pharmacy data, and notification database were accessed to analyze trends of syphilis and sociodemographic, epidemiological and clinical variables associated with reinfection of syphilis. After univariate analysis, a hierarchical logistic regression model was adjusted to analyze variables associated with more than one episode of syphilis (dependent variable). First step (sex, age, and years of schooling) were tested and in the second, epidemiological and clinical variables.

RESULTS

A total of 1,009 episodes of syphilis were identified among 860 adolescents and adults, 117 individuals (13.6%) presented with more than one episode of syphilis. Factors associated with more than one episode of syphilis were sex (male) (OR = 4.28; 95%CI 1.31–14.0), age (OR = 1.02; 95%CI 1.00–1.04), homosexual/bisexual orientation (OR = 2.29; 95%CI 1.22–4.32), HIV coinfection (OR = 3.54; 95%CI 2.22–5.63), and absence of STI symptoms at the time of syphilis diagnostic (OR = 1.70; 95%CI 1.03–2.80).

CONCLUSIONS

The number of cases of syphilis and proportion in relation to STI increased in recent years in a specific population attended in a STI/AIDS reference centers in Campinas. Association with HIV, homosexual/bisexual orientation and the silent clinical characteristic of cases confirm the necessity to implement more aggressive strategies to prevent the occurrence of syphilis and other STI in specific populations with higher disease risk.

Functional clues from the crystal structure of an orphan periplasmic ligand-binding protein from Treponema pallidum

The spirochete Treponema pallidum is the causative agent of syphilis, a sexually transmitted infection of major global importance. Other closely related subspecies of Treponema also are the etiological agents of the endemic treponematoses, such as yaws, pinta, and bejel. The inability of T. pallidum and its close relatives to be cultured in vitro has prompted efforts to characterize T. pallidum's proteins structurally and biophysically, particularly those potentially relevant to treponemal membrane biology, with the goal of possibly revealing the functions of those proteins. This report describes the structure of the treponemal protein Tp0737; this polypeptide has a fold characteristic of a class of periplasmic ligand-binding proteins associated with ABC-type transporters. Although no ligand for the protein was observed in electron-density maps, and thus the nature of the native ligand remains obscure, the structural data described herein provide a foundation for further efforts to elucidate the ligand and thus the function of this protein in T. pallidum.

The Tp0684 (MglB-2) Lipoprotein of Treponema pallidum: A Glucose-Binding Protein with Divergent Topology

Treponema pallidum, the bacterium that causes syphilis, is an obligate human parasite. As such, it must acquire energy, in the form of carbon sources, from the host. There is ample evidence that the principal source of energy for this spirochete is D-glucose acquired from its environment, likely via an ABC transporter. Further, there is genetic evidence of a D-glucose chemotaxis system in T. pallidum. Both of these processes may be dependent on a single lipidated chemoreceptor: Tp0684, also called TpMglB-2 for its sequence homology to MglB of Escherichia coli. To broaden our understanding of this potentially vital protein, we determined a 2.05-Å X-ray crystal structure of a soluble form of the recombinant protein. Like its namesake, TpMglB-2 adopts a bilobed fold that is similar to that of the ligand-binding proteins (LBPs) of other ABC transporters. However, the protein has an unusual, circularly permuted topology. This feature prompted a series of biophysical studies that examined whether the protein's topological distinctiveness affected its putative chemoreceptor functions. Differential scanning fluorimetry and isothermal titration calorimetry were used to confirm that the protein bound D-glucose in a cleft between its two lobes. Additionally, analytical ultracentrifugation was employed to reveal that D-glucose binding is accompanied by a significant conformational change. TpMglB-2 thus appears to be fully functional in vitro, and given the probable central importance of the protein to T. pallidum's physiology, our results have implications for the viability and pathogenicity of this obligate human pathogen.

Syphilis Trends among Men Who Have Sex with Men in the United States and Western Europe: A Systematic Review of Trend Studies Published between 2004 and 2015

Globally, men who have sex with men (MSM) are disproportionately burdened with syphilis. This review describes the published literature on trends in syphilis infections among MSM in the US and Western Europe from 1998, the period with the fewest syphilis infections in both geographical areas, onwards. We also describe disparities in syphilis trends among various sub-populations of MSM. We searched electronic databases (Medline, Embase, Global Health, PsychInfo, CAB Abstracts, CINAHL, Sociological Abstracts, Web of Science, Cochrane Library, and LILACS) for peer-reviewed journal articles that were published between January 2004 and June 2015 and reported on syphilis cases among MSM at multiple time points from 1998 onwards. Ten articles (12 syphilis trend studies/reports) from the US and eight articles (12 syphilis trend studies/reports) from Western Europe were identified and included in this review. Taken together, our findings indicate an increase in the numbers and rates (per 100,000) of syphilis infections among MSM in the US and Western Europe since 1998. Disparities in the syphilis trends among MSM were also noted, with greater increases observed among HIV-positive MSM than HIV-negative MSM in both the US and Western Europe. In the US, racial minority MSM and MSM between 20 and 29 years accounted for the greatest increases in syphilis infections over time whereas White MSM accounted for most syphilis infections over time in Western Europe. Multiple strategies, including strengthening and targeting current syphilis screening and testing programs, and the prompt treatment of syphilis cases are warranted to address the increase in syphilis infections among all MSM in the US and Western Europe, but particularly among HIV-infected MSM, racial minority MSM, and young MSM in the US.

Spatial epidemiology of the syphilis epidemic in Toronto, Canada

BACKGROUND

Urban centers across Canada and the United States have battled syphilis epidemics with high rates of human immunodeficiency virus (HIV) coinfection for over a decade. We examined the spatial epidemiology of syphilis over time for Toronto (Canada) with the intention of forming new insights and strategies for restoring low syphilis rates.

METHODS

Syphilis incidence rates, HIV-syphilis coinfection, and sexual risk behavior prevalences were estimated and mapped from primary, secondary, early latent syphilis cases reported to Toronto Public Health between January 1, 2006, and December 31, 2010, using ArcGIS 9.0. Geographic clusters of significantly elevated syphilis incidence rates were identified using SaTScan 9.0. The relationship between syphilis incidence rates and sociocultural factors was modeled using the Besag, York, and Mollie model.

RESULTS

Between 2006 and 2010, syphilis incidence rates were high in Toronto's downtown core area, intensified, and spread outward initiating 3 independent outbreak areas. HIV coinfection was high (47%); however, no spatial clustering was identified. Syphilis incidence rates, HIV coinfection, and behavioral risk factors promoting sexually transmitted infection transmission were high outside the core area, suggesting that peripheral sexual networks may be influencing high syphilis infection rates both inside and outside the core.

CONCLUSIONS

Toronto's syphilis epidemic is mature. Response, resources, and intervention activities should target core and noncore areas.

Go big or go home: impact of screening coverage on syphilis infection dynamics

OBJECTIVES

Syphilis outbreaks in urban men who have sex with men (MSM) are an ongoing public health challenge in many high-income countries, despite intensification of efforts to screen and treat at-risk individuals. We sought to understand how population-level coverage of asymptomatic screening impacts the ability to control syphilis transmission.

METHODS

We developed a risk-structured deterministic compartmental mathematical model of syphilis transmission in a population of sexually active MSM. We assumed a baseline level of treatment of syphilis cases due to seeking medical care in all scenarios. We evaluated the impact of sustained annual population-wide screening coverage ranging from 0% to 90% on syphilis incidence over the short term (20 years) and at endemic equilibrium.

RESULTS

The relationship between screening coverage and equilibrium syphilis incidence displayed an inverted U-shape relationship, with peak equilibrium incidence occurring with 20-30% annual screening coverage. Annual screening of 62% of the population was required for local elimination (incidence <1 case per 100 000 population). Results were qualitatively similar in the face of differing programmatic, behavioural and natural history assumptions, although the screening thresholds for local elimination differed. With 6-monthly or 3-monthly screening, the population coverage required to achieve local elimination was reduced to 39% or 23%, respectively.

CONCLUSIONS

Although screening has the potential to control syphilis outbreaks, suboptimal coverage may paradoxically lead to a higher equilibrium infection incidence than that observed in the absence of intervention. Suboptimal screening programme design should be considered as a possible contributor to unsuccessful syphilis control programmes in the context of the current epidemic.

A review of the guidelines for the evaluation and treatment of congenital syphilis

Congenital syphilis (CS) is a disease that continues to persist in the United States despite its preventable nature. Mother-to-child transmission of CS can be avoided with appropriate maternal diagnosis and treatment during the pregnancy. Diagnosing CS and determining the therapeutic course can be challenging. This review covers the recent guidelines for the diagnosis and treatment of CS and the various factors that affect management decisions. These factors include the mother's antenatal management, the infant's clinical presentation and results, laboratory and serologic testing, and more.

Unprotected sexual practices among men who have sex with women and men who have sex with men living with HIV/AIDS in Rio de Janeiro

Combined antiretroviral therapy is now acknowledged for preventing new HIV infections, besides decreasing mortality and morbidity. However, in many Latin America countries the epidemic is still driven by unprotected sexual intercourse. This study aims to describe sexual practices related to HIV/STD and to evaluate factors associated to unprotected sex among men who have sex with women (MSW) and men who have sex with men (MSM) under care at a reference center for HIV in Rio de Janeiro, Brazil. A cross-sectional study, nested in a Brazilian clinical cohort, evaluated the sexual practices of 404 sexually active HIV-positive MSW and men who have MSM. Approximately 30 % of them reported unprotected sexual practices during the 6 months prior to the interview. Most frequent risky practices reported were unprotected vaginal sex among MSW and unprotected receptive anal sex among MSM. Factors increasing the chance of unprotected sexual practices among MSW were the partner's desire of becoming pregnant (OR 2.81; CI 95 %: 1.36-5.95). To have received comments about excessive consumption of alcohol (OR 2.43; CI 95 %: 1.01-5.83), illicit drug use (OR 4.41; CI 95 %: 1.75-11.60) and lived in marital situation (OR 2.10; CI 95 %: 1.09-4.08) were significantly associated with unsafe sexual practices among MSM. The results highlight that health care of men living with HIV, as well as the prevention strategies, must consider the particularities of sexual behavior practiced by people who differ in sexual orientation.

Identifying syphilis risk networks through venue attendance in San Francisco

BACKGROUND

Prioritizing interventions for patients with syphilis who are part of large or interconnected sexual networks may be high yield for partner services, and identifying venues named by patients with syphilis who report high numbers of partners may help identify such networks. In this analysis, we explore differences between interviewed patients with early syphilis regarding where they met sex partners.

METHODS

With a cross-sectional design, we examined the distribution of total reported sex partners from male index patients with early syphilis interviewed through the San Francisco Department of Public Health partner services program and the self-reported venues named as places they met sex partners. Based on the median number of total partners among male cases of syphilis who named each venue, we categorized venues into 3 levels of partner frequency: high (>15 partners reported), medium (6-15 partners reported), and low (<6 partners reported). Interviewed patients with early syphilis were then classified into these venue categories, and sociodemographic and risk behaviors from electronic medical records and interviews were compared using χ tests.

RESULTS

In 2011, 433 male patients with early syphilis named 32 venues. One hundred forty-three (32.3%) patients were categorized as high, 226 (51.0%) as medium, and 74 (16.7%) as low partner frequency venue users. Patients with early syphilis who reported meeting partners at high partner frequency venues were generally older, more likely to be white, have a previous syphilis infection, use methamphetamines in the previous year, and be HIV infected (all P < 0.05) compared with those who reported meeting partners at medium-frequency and low-frequency venues.

CONCLUSIONS

Venues where partners are met may be an appropriate proxy for network membership. Targeting additional resources, outreach, and services to clients who attend high-frequency venues may have a positive impact on syphilis prevention efforts.

What underpins the decline in syphilis in Southern and Eastern Africa? An exploratory ecological analysis

BACKGROUND

AIDS mortality played an important role in the decline in syphilis prevalence in the USA, but its effect on the dramatic reduction in syphilis prevalence in Southern and Eastern Africa has not been explored. In this ecological study, we investigated the extent to which the relationship between syphilis and HIV prevalence at a population level varied between the early and late periods of the HIV epidemic.

METHODS

We performed linear regression analysis to measure the association between the national prevalence of syphilis and the peak-HIV prevalence in the early and late phases of the HIV epidemic in 11 countries of Southern and Eastern Africa.

RESULTS

Our analysis showed a strong positive association between peak-HIV prevalence and syphilis prevalence early in the HIV epidemic (R(2)=0.59; p=0.006). Although only of borderline statistical significance, this linear relationship between HIV prevalence and syphilis prevalence switched to a negative direction late in the HIV epidemic (R(2)=0.32; p=0.07).

CONCLUSIONS

AIDS mortality may have played an important role in the decline in syphilis in this region. Consequently, with AIDS deaths declining in Sub-Saharan Africa, vigilant surveillance of syphilis prevalence will be necessary to detect a potential re-emergence, as has occurred in high-income countries, and to render a timely public health response.

The changing relationship between bacterial STIs and HIV prevalence in South Africa - an ecological study

Prevalence estimates of various bacterial sexually transmitted infections in South Africa have declined considerably since the mid-1990s. Syphilis among pregnant women, for example, declined from 10.8% in 1998 to 2.8% in 2001. We used Pearson's correlation coefficients to estimate the association between the prevalence of syphilis/male urethral discharge/male genital ulcers and the peak HIV prevalence at a district and provincial level in the early and late phases of the HIV epidemic in South Africa. Prevalence estimates of syphilis, male urethral discharge and male genital ulcers during the period preceding the peak HIV prevalence were all positively correlated with the peak HIV prevalence at a provincial level (Pearson's correlation coefficient [r] = 0.83, p = 0.006; r = 0.66, p = 0.052; r = 0.79, 0.011, respectively). These relationships all switched to a negative association later in the HIV epidemic at a provincial level (r = -0.53, p = 0.14; r = -0.73, p = 0.130; r = -0.54, p = 0.027, respectively). AIDS mortality may have played an important role in the decline of bacterial sexually transmitted infections such as syphilis in this region. Consequently, the relatively recent scale-up of antiretroviral therapy may result in a resurgence of syphilis and other sexually transmitted infections as observed in high-income countries.

Syphilis in the modern era: an update for physicians

Syphilis is a complex, systemic disease caused by the spirochete Treponema pallidum. Syphilis is most commonly transmitted sexually or congenitally and can involve nearly every organ system. Its clinical progression involves several well-characterized stages: an incubation period, a primary stage, a secondary stage, a latent stage, and a late or tertiary stage. Syphilis during pregnancy is a leading cause of perinatal mortality in sub-Saharan Africa and can cause spontaneous abortion, stillbirth, prematurity, low birth weight, or congenital syphilis. Penicillin is highly effective against syphilis and remains the treatment of choice. This article reviews the epidemiology, clinical features, diagnostic approach, treatment, and prevention of syphilis.

Screen more or screen more often? Using mathematical models to inform syphilis control strategies

Background

Syphilis incidence among men who have sex with men (MSM) continues to rise despite attempts to increase screening and treatment uptake. We examined the marginal effect of increased frequency versus increased coverage of screening on syphilis incidence in Toronto, Canada.

Methods

We developed an agent-based, network model of syphilis transmission, representing a core population of 2,000 high-risk MSM. Epidemiological and biological parameters were drawn from regional surveillance data and literature-derived estimates. The pre-intervention period of the model was calibrated using surveillance data to identify 1000 credible simulations per strategy. Evaluated strategies included: annual syphilis screening at baseline coverage, increased screening frequency at baseline coverage, and increased coverage of annual screening. Intervention impact was measured as annual prevalence of detected infectious cases and syphilis incidence per year over 10 years.

Results

Of the strategies evaluated, increasing the frequency of syphilis screening to every three months was most effective in reducing reported and incident syphilis infections. Increasing the fraction of individuals tested, without increasing test frequency, resulted a smaller decline in incidence, because reductions in infectious syphilis via treatment were counterbalanced by increased incident syphilis among individuals with prior latent syphilis. For an equivalent number of additional tests performed annually, increased test frequency was consistently more effective than improved coverage.

Conclusions

Strategies that focus on higher frequency of testing in smaller fractions of the population were more effective in reducing syphilis incidence in a simulated MSM population. The findings highlight how treatment-induced loss of immunity can create unexpected results in screening-based control strategies.

Prevalence and epidemiological traits of HIV infections in populations with high-risk behaviours as revealed by genetic analysis of HBV

The prevalence and epidemiological traits of human immunodeficiency virus (HIV)/hepatitis B virus (HBV) infections in high-risk populations (HRPs) remained unclarified in Japan. We determined the prevalence of HIV, HBV and Treponema pallidum (TP) and the viral genotypes in HRPs who attended primary sexually transmitted infection (STI) clinics in Osaka province during 2006-2011. Of 7898 specimens, 133 (1·7%) were HIV positive, which was significantly higher than the figures reported by Japanese Red Cross (0·0019%) and public health centres (0·27%) in Japan. The frequency of HIV-1 subtype B was 88·7%, followed by CRF01_AE (2·3%) and C (0·8%), which were almost identical to the national trend. HBV seroprevalence was surprisingly high in the HIV-positive group (63·2%), which was significantly higher than that in the HIV-negative group (25·6%). By contrast, there was no statistical correlation between HIV and TP infection. Interestingly, the distinct HBV genotypes Ae and G were prevalent in the HIV-positive population (60·0% and 20·0%, respectively), although both were rarely detected during nationwide surveillance. The transmission of HIV and HBV appeared to occur largely within a closed community early in life. Of note, about one-quarter of HIV-positive cases would have remained untested if health professionals had not motivated individuals to undergo HIV testing. This is the first evidence-based assessment of HIV positivity and HIV/HBV co-infection in HRPs at primary STIs in Japan and the effect of the involvement of health professionals in the diagnosis of HIV infections in asymptomatic carriers. The genotyping of HBV provided valuable information for understanding HIV epidemical traits.

Men who have sex with men, infectious syphilis and HIV coinfection in inner Sydney: results of enhanced surveillance

Background The resurgence of infectious syphilis in men who have sex with men (MSM) has been documented worldwide; however, HIV coinfection and syphilis reinfections in MSM in inner Sydney have not been published. Methods: For all laboratory syphilis notifications assessed as a newly notified case or reinfection, a questionnaire was sent to the requesting physician seeking demographic data and disease classification. Sex of partner and HIV status were collected for all infectious syphilis notifications in men received from 1 April 2006 to March 2011. Results: From April 2001 to March 2011, 3664 new notifications were received, 2278 (62%) were classified as infectious syphilis. Infectious syphilis notifications increased 12-fold from 25 to 303 in the first and last year respectively, and almost all notifications were in men (2220, 97.5%). During April 2006 to March 2011, 1562 infectious syphilis notifications in males were received and 765 (49%) of these men were HIV-positive and 1351 (86%) reported a male sex partner. Reinfections increased over time from 17 (9%) to 56 (19%) in the last year of the study and were significantly more likely to be in HIV-positive individuals (χ2 = 140.92, degrees of freedom= 1, P = <0.001). Conclusion: Inner Sydney is experiencing an epidemic of infectious syphilis in MSM and about half of these cases are in HIV-positive patients. Reinfections are increasing and occur predominantly in HIV-positive men. Accurate surveillance information is needed to inform effective prevention programs, and community and clinician education needs to continue until a sustained reduction is achieved.

Would gay men change their sexual behavior to reduce syphilis rates?

BACKGROUND

The community at which public health strategies for reducing syphilis epidemics are potentially targeted may have different considerations with regards to their sexual and health priorities. We aimed to elicit information on the acceptability of behavior change interventions among gay men for reducing syphilis transmission.

METHODS

We conducted an online survey (n = 2306 participants) and focus groups to determine whether further sexual behavior change to reduce syphilis is likely to be acceptable to gay men in Australia.

RESULTS

One quarter of survey respondents (26%) indicated that they would be highly likely to reduce partner acquisition rates in order to reduce their chances of syphilis infection. However, among the 475 (21%) men who reported greater than 10 partners in the previous 6 months, only 11% indicated being "highly likely" to reduce partner numbers to avoid syphilis. Among 606 (26%) survey respondents who reported not always using condoms in the previous 6 months, 34% indicated being highly likely to always use condoms with casual partners to avoid syphilis. In the focus groups, men indicated little commitment to sexual behavior change but some willingness to consider short-term changes to reduce community syphilis levels.

CONCLUSIONS

Interventions promoting partner reduction or increased condom use are unlikely to be adopted on a long-term basis by men at greatest risk. Behavioral interventions alone are unlikely to materially contribute to syphilis prevention among gay men.

Will changes in gay men's sexual behavior reduce syphilis rates?

BACKGROUND

Reducing rates of partner change and increasing condom usage among gay men are obvious targets for potentially reducing syphilis transmission among gay men.

METHODS

We developed an agent-based stochastic model to examine syphilis transmission among a population of gay men, representative of gay men in Australia. This model was used to explore the potential impact of changes in sexual behavior over 1 month, 3 month, and indefinite time frames on syphilis epidemics.

RESULTS

Simulations of interventions showed that short-term reductions in rates of partner change and increased condom use would have negligible impact on the long-term trends of syphilis epidemics. If no interventions are introduced, then the model forecasts that the syphilis prevalence in the population could continue to rise, with an increase of 80% in the number of men infected with syphilis during the next decade. However, if changes in sexual behavior are maintained in the long-term, then syphilis epidemics can be mitigated. If condom use is sustained at 80% in partnerships that are HIV discordant or of unknown status, then the prevalence of syphilis is estimated to decrease by 9% over 10 years. Similarly, if partner acquisition rates decrease by 25%, then there will be a 22% reduction in syphilis prevalence.

CONCLUSIONS

Interventions promoting partner reduction or increased condom use would be ineffective in the short-term, and would have limited prospects for success in the long-term unless very large changes in behavior are sustained. Complementary social research indicates that such long-term changes in behavior are unlikely to be adopted, and therefore other intervention strategies need to be developed to reduce syphilis among gay men.

Sexually transmitted diseases in men who have sex with men

Men who have sex with men (MSM) have increased rates of human immunodeficiency virus (HIV) infection and sexually transmitted diseases (STDs) compared with demographically matched controls. The reasons for the disproportionate infection burden are complex, including biological, behavioral, and sociocultural factors. HIV and syphilis may often be coprevalent among MSM. The use of nucleic acid amplification testing has enhanced the ability to detect frequently asymptomatic gonococcal and chlamydial infections of the rectum and other sites. Lymphogranuloma proctitis outbreaks among MSM were noted in the developed world several years ago but have not been common recently. MSM are at increased risk for viral hepatitis and anal human papillomavirus disease. Preventive interventions include vaccination for the former and anal cytologic screening for the latter. Because of the diverse ways in which MSM may be exposed to STDs, it is essential for clinicians to obtain a thorough sexual history in a culturally competent manner.

Needle in a haystack: the yield of syphilis outreach screening at 5 US sites-2000 to 2007

BACKGROUND

Screening for syphilis has been performed for decades, but it is unclear if the practice yields many cases at acceptable cost, and if so, at which venues. We attempted a retrospective study to determine the costs, yield, and feasibility of analyzing health department-funded syphilis outreach screening in 5 diverse US sites with significant disease burdens.

METHODS

Data (venue, costs, number of tests, reactive tests, new diagnoses) from 2000 to 2007 were collected for screening efforts funded by public health departments from Philadelphia; New York City; Washington, District of Columbia; Maricopa County, Arizona (Phoenix); and the state of Florida. Crude cost per new case was calculated.

RESULTS

Screening was conducted in multiple venues including jails, shelters, clubs, bars, and mobile vans. Over the study period, approximately 926 258 tests were performed and 4671 new syphilis cases were confirmed, of which 225 were primary and secondary, and 688 were early latent or high-titer late latent. Jail intake screening consistently identified the largest numbers of new cases (including 67.6% of early and high-titer late-latent cases) at a cost per case ranging from $144 to $3454. Data quality from other venues varied greatly between sites and was often poor.

CONCLUSIONS

Though the yield of jail intake screening was good, poor data quality, particularly cost data, precluded accurate cost/yield comparisons at other venues. Few cases of infectious syphilis were identified through outreach screening at any venue. Health departments should routinely collect all cost and testing data for screening efforts so that their yield can be evaluated.

Increased syphilis trend among patients in an AIDS information and prevention center

OBJECTIVE

A rebound of syphilis cases has recently been observed. This study describes the trend in syphilis infection among persons attending the AIDS information and prevention center of Valencia, Spain.

METHODS

We performed a cohort study of all persons attended from 2000 to 2006. The calendar effect was assessed by a logistic regression model adjusted by sexual and sociodemographic variables.

RESULTS

A total of 71% were heterosexuals (HT) and 19% were men who had sex with men (MSM). Among the 10,850 users of the center, the prevalence of syphilis was 0.7%. Among MSM, the prevalence of syphilis was 2.4% for the whole period and was 4.6% for 2006. Multivariate analysis showed that the risk of infection was lower in persons with a university education (OR=0.10; 95%CI: 0.03-0.59) than in those without. The risk was higher in persons who took drugs (OR=5.49; 95%CI: 1.55-19.43) or who practiced prostitution (OR=6.83; 95%CI: 2.52-18.53). In 2006, the risk of having syphilis was greater (OR=5.05; 95%CI: 1.12-22.72).

CONCLUSIONS

Syphilis infection increased substantially among MSM. In this collective, the prevalence of infection is related to educational level, prostitution and the use of non-injected recreational drugs.

Posterior placoid chorioretinitis: An unusual ocular manifestation of syphilis

There appears to be a re-emergence of syphilis in recent times despite a steady decline in incidence for the past decade. Diagnosis of syphilis can be clinically challenging and ocular manifestations of syphilis have a myriad of presentations and severity. Ocular syphilis can occur at any stage of the disease and may also be the only presenting sign of syphilis. We report a case of acute unilateral maculopathy, due to posterior placoid chorioretinitis associated with syphilis, in an immunocompetent patient. Ophthalmoscopy revealed a unilateral yellowish placoid lesion at the macula. Syphilis serology was positive confirming active infection. There were no other systemic signs of syphilis. The patient was treated with intravenous benzylpenicillin 1.2 g every four hours for two weeks. The lesion resolved with treatment and the retinal appearance returned to normal. This case highlights the importance of raising clinical suspicion of syphilis in view of unexplained decreased vision and ocular inflammation.

Sexual health, HIV, and sexually transmitted infections among gay, bisexual, and other men who have sex with men in the United States

The sexual health of gay, bisexual, and other men who have sex with men (MSM) in the United States is not getting better despite considerable social, political and human rights advances. Instead of improving, HIV and sexually transmitted infections (STIs) remain disproportionately high among MSM and have been increasing for almost two decades. The disproportionate and worsening burden of HIV and other STIs among MSM requires an urgent re-assessment of what we have been doing as a nation to reduce these infections, how we have been doing it, and the scale of our efforts. A sexual health approach has the potential to improve our understanding of MSM's sexual behavior and relationships, reduce HIV and STI incidence, and improve the health and well-being of MSM.

Improving partner services by embedding disease intervention specialists in HIV-clinics

BACKGROUND/OBJECTIVES

Notifying partners of HIV-infected persons and referring them for testing and treatment is an effective method of disease control and identification of undiagnosed STD and/or HIV. To improve partner elicitation interviews, disease intervention specialists (DIS) were placed in 3 HIV clinics during 2008 and 2009.

METHODS

We reviewed the Arizona state STD surveillance database for 2007 to identify the providers (outside of the public STD clinics) reporting the highest number of syphilis cases. DIS were placed in the clinics for half a day per week (2 clinics) or on an on-call basis (1 clinic) to deliver penicillin and interview patients. We calculated changes in the number of patients interviewed, days elapsed from specimen collection to treatment (time to treatment), days elapsed from specimen collection to initial DIS contact (time to interview), and number of reported and locatable partners from these 3 clinics before and after the clinic placement of DIS.

RESULTS

Before the placement of clinic-based DIS, 219 syphilis cases were diagnosed at the 3 clinics (January 2006 through January 2008). After DIS placement, 115 syphilis cases were diagnosed (February 2008 through September 2009) for a total of 334 cases in this analysis. A greater percent of patients completed a partner elicitation interview during the period of DIS placement (94% after vs. 81% before, P = 0.001). There were increases in the average number of locatable partners (1.1 after vs. 0.6 before, P = 0.004) and an increase in the average number of partners exposed and brought to treatment (CDC Disposition A) or infected and brought to treatment (CDC Disposition C) (0.6 after vs. 0.3 before, P = 0.02), and the time to interview decreased (18 days before vs. 9 days after, P = 0.02).

CONCLUSIONS/IMPLICATIONS

Placing DIS within community HIV clinics improved partner services. STD and/or HIV programs should consider this method to improve partner notification.

The role of commercial sex venues in the HIV epidemic among men who have sex with men

BACKGROUND

Commercial sex venues such as bathhouses and sex clubs have long been considered important facilitators of HIV transmission among men who have sex with men in the United States. Recent probability surveys of commercial-sex-venue patrons in King County, WA that included data on behavior both within and outside these venues provide an empirical basis for the development of mathematical models to estimate the role that commercial sex venues play in the HIV epidemic.

METHODS

We constructed deterministic compartmental mathematical models of HIV transmission to estimate both current incidence among King County men who have sex with men and incidence in 5 counterfactual scenarios in which commercial-sex-venues were presumed not to exist. We parameterized the models using a range of values for the proportion of commercial sex venues partnerships replaced in the absence of these venues, and the number of acts of unprotected anal intercourse per other types of partnership. Yearly attributable number was calculated as the difference between incident HIV cases in the main models and each corresponding counterfactual model. We performed extensive sensitivity analyses using Latin hypercube sampling.

RESULTS

Replacement of 25% of commercial sex venue partners in the absence of these venues resulted in attributable number values near zero per year. Replacement of 50% or more of commercial sex venue partners resulted in negative yearly attributable numbers, indicating a net increase in incident HIV infections in the absence of these venues. Results of the sensitivity analyses were consistent with the main findings.

CONCLUSIONS

Our findings imply that commercial sex venues contribute little to the burden of HIV among men who have sex with men in King County, WA.

High incidence of asymptomatic syphilis in HIV-infected MSM justifies routine screening

BACKGROUND

Recently, the incidence of syphilis has risen, mainly among men having sex with men (MSM), many of whom are coinfected with HIV. Current guidelines recommend at least yearly syphilis testing in this group. In this study, we assessed the yield of routine syphilis screening in outpatient HIV-patients.

METHODS

From March through June 2003, syphilis serology was routinely performed in HIV-infected patients visiting our outpatient clinic. Serology was repeated six months later. Positive test results of the first episode were compared to historical test results (retrospective analysis). Test results of the second episode were compared to test results from the first episode (prospective analysis). Case records of all patients with a new infection were reviewed for symptomatic disease or testing because of syphilis contacts, versus asymptomatic disease.

RESULTS

In the retrospective analysis, 1,105 patients were included. In 68 patients, 81 syphilis infections were identified, of which 33% asymptomatic. 77/81 infections were acquired between 2000 and 2003, resulting in a total incidence of 2.7/100 person years (PY) of follow-up, and 0.9/100 PY for asymptomatic disease. In MSM, the incidence rate was 4.6/100 and 1.5/100 PY respectively. In the prospective analysis, 1,010 patients were included. Seventeen patients, all MSM, had a new or recurrent syphilis infection, of whom 4 asymptomatic, accounting for a total event rate of 3.5/100 PY. In MSM, the event rate was 6.2/100 PY, with an incidence of asymptomatic disease of 1.4/100 PY.

CONCLUSION

Routine screening for syphilis identifies significant numbers of asymptomatic syphilis infection in HIV-infected MSM.

Trends in hepatitis A, B, and shigellosis compared with gonorrhea and syphilis in men who have sex with men in Amsterdam, 1992-2006

BACKGROUND

Since the mid-1990s, sexually transmitted infections (STIs) among men who have sex with men (MSM) have increased and appear to be related to more risky sexual behavior. We compare trends in hepatitis A, acute hepatitis B, and shigellosis with the trends of gonorrhea and infectious syphilis in Amsterdam MSM more than a period of 15 years.

METHODS

We used data of all reported hepatitis A, acute hepatitis B, and shigellosis, and from all patients newly diagnosed with gonorrhea and infectious syphilis who visited the Public Health Service STI outpatient department in Amsterdam between January 1, 1992 and December 31, 2006.

RESULTS

Hepatitis A incidence remained unchanged in MSM (mean 0.97 per 1000 MSM, range 0.04-2.27), who had 21% of all 1697 infections. Hepatitis B likewise remained unchanged in MSM (mean 0.47 per 1000 MSM, range 0.19-0.77), who had 41% of all 448 infections. Most shigellosis is travel-related (657/974), and 16% of the infections occurred in MSM. Its incidence dropped in general, but not in MSM. Both gonorrhea and infectious syphilis in MSM show a steep increase, mainly after 1998.

DISCUSSION

Hepatitis A, B, and shigellosis do not follow the rising trends of conventional STI in MSM, which are believed to result from increased risky sexual behavior. This disparity in trends implies differences in transmission dynamics. Recent molecular epidemiologic studies suggest that clustered transmission in social MSM networks plays a major role.

Evaluation of test results of microbiology laboratories of North India for standard tests for syphilis under an external quality assurance scheme

Test results of syphilis serology are critical due to inter- and intralaboratory variability. The accuracy of results is crucial in the control of the disease. This study was aimed to compare results of laboratories and performance of methods for syphilis serology. Results of Veneral Disease Reference Laboratory (VDRL) or rapid plasma reagin (RPR) tests of 25 microbiology laboratories were compared in six proficiency testing sentinel surveys. The performance of laboratories was compared with the results of a hypothetical average laboratory. Of the 141 participants, 104 (73.8%) responded. The inter-laboratory variability was exhibited by 62.2% of samples tested by VDRL and 58.7% by RPR test. Intralaboratory variability was observed in 46.7% samples. There was an insignificant improvement in proficiency testing (PT) performance over the years with a significant improvement in 2007. The common errors involved departure from testing protocols. Syphilis serology proficiency testing is needed in India for reliability in test results.

Factors associated with newly diagnosed HIV among persons with concomitant sexually transmitted diseases

OBJECTIVE

We evaluated Illinois and Chicago Departments of Public Health surveillance databases to determine risk factors associated with newly diagnosed HIV among persons with bacterial sexually transmitted diseases (STDs).

METHODS

Test results for Chlamydia, gonorrhea, early syphilis (primary, secondary, and early latent), and HIV from public health clinics in Illinois in 2002 were merged with demographic and behavioral survey data collected during patient visits. STD was defined as any positive non-HIV result.

RESULTS

Among 43,517 patient encounters, 5814 (13.4%) had positive STD test results. There were 308 (0.7%) positive new HIV test results, of which 71 (23.1%) had concomitant infection with an STD. Compared with STD-positive, HIV-negative cases, age >30 years (OR = 1.9, 95% CI, 1.0,4.4), men who have sex with men (MSM) (OR = 22.2, 95% CI 11.3-43.7), and bisexual male (OR = 22.4, 95% CI 7.8-64.8) were independently associated with STD and HIV coinfections. Among distinct STDs, syphilis (n = 438) was the least frequent (7.5%), but was reported in the highest proportion (10.1%) of all new HIV infections and conferred the greatest risk (OR = 11.0, 95% CI 7.7-15.8) for newly diagnosed HIV.

CONCLUSIONS

MSM were at increased risk for newly diagnosed HIV with STD coinfection. Persons with a concomitant STD and HIV were older than US populations that generally constitute the greatest proportion of STD cases. These results highlight the role in particular of syphilis among populations at high risk for HIV transmission. Public health interventions targeting MSM and older adults for effective testing and prevention strategies are critically needed within high-risk networks for cotransmission of STDs and HIV.

Formulas for estimating the costs averted by sexually transmitted infection (STI) prevention programs in the United States

Background

Sexually transmitted infection (STI) prevention programs can mitigate the health and economic burden of STIs. A tool to estimate the economic benefits of STI programs could prove useful to STI program personnel.

Methods

We developed formulas that can be applied to estimate the direct medical costs and indirect costs (lost productivity) averted by STI programs in the United States. Costs and probabilities for these formulas were based primarily on published studies.

Results

We present a series of formulas that can be used to estimate the economic benefits of STI prevention (in 2006 US dollars), using data routinely collected by STI programs. For example, the averted sequelae costs associated with treating women for chlamydia is given as (C_w)(0.16)(0.925)(0.70)($1,995), where C_w is the number of infected women treated for chlamydia, 0.16 is the absolute reduction in the probability of pelvic inflammatory disease (PID) as a result of treatment, 0.925 is an adjustment factor to prevent double-counting of PID averted in women with both chlamydia and gonorrhea, 0.70 is an adjustment factor to account for the possibility of re-infection, and $1,995 is the average cost per case of PID, based on published sources.

Conclusion

The formulas developed in this study can be a useful tool for STI program personnel to generate evidence-based estimates of the economic impact of their program and can facilitate the assessment of the cost-effectiveness of their activities.

Partner Notification for Gonococcal and Chlamydial Infections in Men Who Have Sex With Men: Success Is Underestimated by Traditional Disposition Codes

BACKGROUND

Recent reports evaluating partner notification (PN) efforts among men who have sex with men (MSM) have observed relatively poor outcomes. However, the validity of traditional PN disposition codes is not known, possibly leading to overly pessimistic assessments of PN outcomes.

OBJECTIVES

To evaluate PN practices among MSM with gonococcal or chlamydial infection, assess the utility of offering MSM PN assistance and compare patient self-reported PN outcomes with those recorded using Disease Intervention Specialist (DIS) disposition codes.

STUDY DESIGN

We reviewed the records of all MSM with gonococcal or chlamydial infection interviewed by Public Health-Seattle and King County for purposes of PN in 2004. Men were asked to indicate whether each of their sex partners were already notified or treated at time of interview and were offered PN assistance.

RESULTS

DIS interviewed 409 of 628 (65%) MSM reported with gonococcal or chlamydial infection. Three hundred thirteen of the 409 (76%) interviewed men provided information about their number of sex partners in the 60 days before diagnosis and specific information about 1 or more of their potentially exposed partners. These index cases reported a total of 1037 sex partners, but provided information about only 634 (61%). Two hundred thirteen of the 313 (68%) index cases reported notifying at least 1 partner. Index cases reported that 295 of all 1037 (28%) reported partners had been notified, and that 170 (16%) were treated; DIS disposition codes documented the treatment of 111 (11%) partners. Only 18 (6%) index cases requested DIS assistance contacting a partner; DIS notified and assured the treatment of 24 of the 35 (69%) partners reported by these 18 men.

CONCLUSIONS

Although MSM with gonorrhea or chlamydia seldom accept assistance notifying partners, they report higher levels of partner treatment than suggested by DIS disposition codes, with 68% indicating that they had notified at least 1 sex partner and 46% reporting that at least 1 of their partners received treated.

Structural and biochemical basis for polyamine binding to the Tp0655 lipoprotein of Treponema pallidum: putative role for Tp0655 (TpPotD) as a polyamine receptor

Tp0655 of Treponema pallidum, the causative agent of syphilis, is predicted to be a 40 kDa membrane lipoprotein. Previous sequence analysis of Tp0655 noted its homology to polyamine-binding proteins of the bacterial PotD family, which serve as periplasmic ligand-binding proteins of ATP-binding-cassette (ABC) transport systems. Here, the 1.8 A crystal structure of Tp0655 demonstrated structural homology to Escherichia coli PotD and PotF. The latter two proteins preferentially bind spermidine and putrescine, respectively. All of these proteins contain two domains that sandwich the ligand between them. The ligand-binding site of Tp0655 can be occupied by 2-(N-morpholino)ethanesulfanoic acid, a component of the crystallization medium. To discern the polyamine binding preferences of Tp0655, the protein was subjected to isothermal titration calorimetric experiments. The titrations established that Tp0655 binds polyamines avidly, with a marked preference for putrescine (Kd=10 nM) over spermidine (Kd=430 nM), but the related compounds cadaverine and spermine did not bind. Structural comparisons and structure-based sequence analyses provide insights into how polyamine-binding proteins recognize their ligands. In particular, these comparisons allow the derivation of rules that may be used to predict the function of other members of the PotD family. The sequential, structural, and functional homology of Tp0655 to PotD and PotF prompt the conclusion that the former likely is the polyamine-binding component of an ABC-type polyamine transport system in T. pallidum. We thus rename Tp0655 as TpPotD. The ramifications of TpPotD as a polyamine-binding protein to the parasitic strategy of T. pallidum are discussed.