Two mutations associated with macrolide resistance in Treponema pallidum: increasing prevalence and correlation with molecular strain type in Seattle, Washington

Molecular characterization of Treponema pallidum isolates from Brazil

Syphilis remains a public health concern in Brazil, and the data on the characterization and resistance of Treponema pallidum in Brazil is limited. The present study aimed to detect Treponema DNA in the lesions and blood samples obtained from individuals diagnosed with syphilis. The Brazilian isolates were submitted to the Enhanced Centers for Disease Control and Prevention (ECDC) scheme and also analyzed for resistance gene. Treponemal DNA from 18 lesions and 18 blood specimens were submitted for amplification using Polymerase Chain Reaction (PCR) and Polymerase Chain Reaction in Real Time (RT-PCR). Eight samples from lesions and eight from blood were positive in the RT-PCR analysis. Eight lesions and three blood samples were positive using PCR. Two samples exhibited azithromycin resistance. The Brazilian isolate types 14d/g, 14 d/c, 15d/c, and 15d/e were identified using the ECDC scheme. The three subtypes 14d/c, 15d/c, and 15d/e have been identified in Brazil for the first time.

Important considerations regarding the widespread use of doxycycline chemoprophylaxis against sexually transmitted infections

Rates of sexually transmitted infections (STIs) continue to rise across the world and interventions are essential to reduce their incidence. Past and recent studies have indicated this may be achieved using doxycycline post-exposure prophylaxis (PEP) and this has sparked considerable interest in its use. However, many unanswered questions remain as to its long-term effects and particularly potentially negative impact on human microbiomes and antimicrobial resistance among STIs, other pathogens, and commensals. In this review, we discuss seven areas of concern pertaining to the widespread use of doxycycline PEP.

Syphilis as Re-Emerging Disease, Antibiotic Resistance, and Vulnerable Population: Global Systematic Review and Meta-Analysis

Syphilis is a sexually transmitted disease that has become a public health problem, especially in vulnerable populations. A systematic review and time-free meta-analysis of the publications on the molecular detection of syphilis and mutations associated with antibiotic resistance, CORE group, and syphilis genotypes in PubMed databases, Scielo, and Cochrane was performed, and the last search was conducted in June 2022. Proportions were calculated, and standard errors and confidence intervals were reported for all results of interest. We included 41 articles for quantitative extraction and data synthesis. An increase was observed in the proportion of subjects diagnosed with syphilis and the presence of the A2058G mutation during the 2018−2021 period compared to 2006 (70% 95%CI 50−87 vs. 58% 95%CI 12−78), and we observed that the greater the proportion of the population participating in men who have sex with men (MSM) (<50% and >50%) syphilis increased (78% 95%CI 65−90 vs. 33% 95%CI 19−49). In conclusion, we suggest that there are a set of characteristics that are contributing to the resurgence of syphilis and the selective pressure of bacteria. The MSM population could be a vulnerable factor for this scenario and the global presence of A2058G and A2059G mutations that confer resistance to macrolides.

Mathematical modelling Treponema infection in free-ranging Olive baboons (Papio anubis) in Tanzania

Yaws is a chronic infection caused by the bacterium Treponema pallidum susp. pertenue (TPE) that was thought to be an exclusive human pathogen but was recently found and confirmed in nonhuman primates. In this paper, we develop the first compartmental ODE model for TPE infection with treatment of wild olive baboons. We solve for disease-free and endemic equilibria and give conditions on local and global stability of the disease-free equilibrium. We calibrate the model based on the data from Lake Manyara National Park in Tanzania. We use the model to help the park managers devise an effective strategy for treatment. We show that an increasing treatment rate yields a decrease in disease prevalence. This indicates that TPE can be eliminated through intense management in closed population. Specifically, we show that if the whole population is treated at least once every 5-6 years, a disease-free equilibrium can be reached. Furthermore, we demonstrate that to see a substantial decrease of TPE infection to near-elimination levels within 15 years, the whole population needs to be treated every 2-3 years.

High frequency of Nichols-like strains and increased levels of macrolide resistance in Treponema pallidum in clinical samples from Buenos Aires, Argentina

Globally, 94% of Treponema pallidum subsp. pallidum (TPA) clinical strains belong to the SS14-like group and 6% to the Nichols-like group, with a prevalence of macrolide resistance of 90%. Our goal was to determine whether local TPA strain distribution and macrolide resistance frequency have changed significantly since our last report, which revealed that Buenos Aires had a high frequency of Nichols-like strains (27%) and low levels of macrolide resistance (14%). Swab samples from patients with suspected syphilis were collected during 2015–2019 and loci TP0136, TP0548, TP0705 were sequenced in order to perform multilocus sequence typing. Strains were classified as Nichols-like or SS14-like. The presence of macrolide resistance-associated mutations was determined by examination of the 23S rDNA gene sequence. Of 46 typeable samples, 37% were classified as Nichols-like and 63% as SS14-like. Macrolide resistance prevalence was 45.7%. Seven allelic profiles were found, five were SS14-like and two were Nichols-like. The frequency of Nichols-like strains increased between studies (26.8% vs. 37%, p = 0.36). A dramatic increase was found in the frequency of macrolide resistant strains between studies (14.3% vs. 45.7%, p = 0.005). Our results are in agreement with international trends and underscore the need to pursue further TPA molecular typing studies in South America.

High-throughput nanopore sequencing of Treponema pallidum tandem repeat genes arp and tp0470 reveals clade-specific patterns and recapitulates global whole genome phylogeny

Sequencing of most Treponema pallidum genomes excludes repeat regions in tp0470 and the tp0433 gene, encoding the acidic repeat protein (arp). As a first step to understanding the evolution and function of these genes and the proteins they encode, we developed a protocol to nanopore sequence tp0470 and arp genes from 212 clinical samples collected from ten countries on six continents. Both tp0470 and arp repeat structures recapitulate the whole genome phylogeny, with subclade-specific patterns emerging. The number of tp0470 repeats is on average appears to be higher in Nichols-like clade strains than in SS14-like clade strains. Consistent with previous studies, we found that 14-repeat arp sequences predominate across both major clades, but the combination and order of repeat type varies among subclades, with many arp sequence variants limited to a single subclade. Although strains that were closely related by whole genome sequencing frequently had the same arp repeat length, this was not always the case. Structural modeling of TP0470 suggested that the eight residue repeats form an extended α-helix, predicted to be periplasmic. Modeling of the ARP revealed a C-terminal sporulation-related repeat (SPOR) domain, predicted to bind denuded peptidoglycan, with repeat regions possibly incorporated into a highly charged β-sheet. Outside of the repeats, all TP0470 and ARP amino acid sequences were identical. Together, our data, along with functional considerations, suggests that both TP0470 and ARP proteins may be involved in T. pallidum cell envelope remodeling and homeostasis, with their highly plastic repeat regions playing as-yet-undetermined roles.

Treponema pallidum genome sequencing from six continents reveals variability in vaccine candidate genes and dominance of Nichols clade strains in Madagascar

In spite of its immutable susceptibility to penicillin, Treponema pallidum (T. pallidum) subsp. pallidum continues to cause millions of cases of syphilis each year worldwide, resulting in significant morbidity and mortality and underscoring the urgency of developing an effective vaccine to curtail the spread of the infection. Several technical challenges, including absence of an in vitro culture system until very recently, have hampered efforts to catalog the diversity of strains collected worldwide. Here, we provide near-complete genomes from 196 T. pallidum strains-including 191 T. pallidum subsp. pallidum-sequenced directly from patient samples collected from 8 countries and 6 continents. Maximum likelihood phylogeny revealed that samples from most sites were predominantly SS14 clade. However, 99% (84/85) of the samples from Madagascar formed two of the five distinct Nichols subclades. Although recombination was uncommon in the evolution of modern circulating strains, we found multiple putative recombination events between T. pallidum subsp. pallidum and subsp. endemicum, shaping the genomes of several subclades. Temporal analysis dated the most recent common ancestor of Nichols and SS14 clades to 1717 (95% HPD: 1543-1869), in agreement with other recent studies. Rates of SNP accumulation varied significantly among subclades, particularly among different Nichols subclades, and was associated in the Nichols A subclade with a C394F substitution in TP0380, a ERCC3-like DNA repair helicase. Our data highlight the role played by variation in genes encoding putative surface-exposed outer membrane proteins in defining separate lineages, and provide a critical resource for the design of broadly protective syphilis vaccines targeting surface antigens.

A Comparison of Treponema pallidum Subspecies pallidum Molecular Typing Systems: Multilocus Sequence Typing vs. Enhanced Centers for Disease Control and Prevention Typing

BACKGROUND

At least 3 syphilis typing systems are proposed. Recent work suggests that multilocus sequence typing (MLST) may be superior to enhanced Centers for Disease Control and Prevention typing (ECDCT) by yielding a higher discriminatory power. The goal of this study was to compare the 2 systems and identify associations between neurosyphilis and strain types.

METHODS

Multilocus sequence typing for tp0136, tp0548, and tp0705 was determined for DNA from 78 Treponema pallidum subspecies pallidum isolates propagated in rabbits, 10 oral and 10 genital or non-genital lesion swabs, and 10 blood samples from patients with syphilis. These samples were chosen because they were completely typeable by ECDCT. Using both systems, association between strain types and neurosyphilis, defined as a reactive cerebrospinal fluid Venereal Disease Research Laboratory test, was determined. Partial and complete ECDCT types were also determined for samples from different anatomical sites in 35 patients, and from blood and blood isolates (rabbit propagated) from 13 patients.

RESULTS

The MLST type could be fully determined for 100 (92.6%) of 108 samples. Although MLST subdivided 3 common ECDCT types, it failed to distinguish among others. Neurosyphilis was more common in individuals infected with type 1.1.2 and tp0705 type 2 using MLST, and tp0548 type f using ECDCT. Enhanced Centers for Disease Control and Prevention typing was stable among anatomical sites and between patient-derived and rabbit propagated organisms.

CONCLUSIONS

Compared with ECDCT, MLST was not uniformly more discriminating. Both typing systems demonstrate that specific types may be more neurotropic than others.

Treponema pallidum macrolide resistance and molecular epidemiology in southern Africa, 2008-2018

Treponema pallidum macrolide resistance and clinical treatment failure have emerged rapidly within communities where macrolides have been used as convenient, oral therapeutic alternatives to benzathine penicillin G for syphilis, or for other clinical indications. Macrolides are not included in the South African syndromic management guidelines for genital ulcer disease; however, in 2015, a 1 gram dose of azithromycin was incorporated into treatment algorithms for genital discharge. We determined the prevalence of 23S rRNA macrolide resistance-associated point mutations in 135 T. pallidum-positive surveillance specimens from Botswana, Zimbabwe and South Africa between 2008 and 2018. Additionally, we investigated the association between macrolide resistance, T. pallidum strain type and HIV co-infection. A significant increase in the prevalence of the A2058G macrolide resistance-associated point mutation was observed in specimens collected after 2015. There was a high level of molecular heterogeneity among T. pallidum strains circulating in the study communities, with strain type 14d/f being the most predominant in South Africa. Fourteen novel strain types, derived from three new tpr-gene restriction fragment length polymorphism patterns and seven new tp0548-gene sequence types, were identified. There was an association between A2058G-associated macrolide resistance and T. pallidum strain types 14d/f and 14d/g, but no association between T. pallidum macrolide resistance and HIV co-infection. The majority of T. pallidum strains, as well as strains containing the A2058G mutation, belonged to the SS14-like clade. This is the first study to extensively detail the molecular epidemiology and emergence of macrolide resistance in T. pallidum in southern Africa.

Should we still use azithromycin for gonorrhoea treatment?

This review presents the evidence for azithromycin in the treatment of gonorrhoea, both as monotherapy and as a component of dual therapy. Uncertainties are explored regarding the efficacy of a dual treatment strategy, combining ceftriaxone and azithromycin, in the context of resistance trends and extra-genital infections. The association between microbiological testing and clinical outcome for the individual patient, and the effect of azithromycin use on other sexually transmissible infections, are considered. Finally, in the absence of imminent new antimicrobials, optimising the dose of azithromycin while maintaining tolerability is discussed.

Increased Discrimination of Treponema pallidum Strains by Subtyping With a 4-Component System Incorporating a Mononucleotide Tandem Repeat in rpsA

A guanine mononucleotide repeat in the rpsA (tp0279) gene was evaluated for improved strain discrimination using 72 Treponema pallidum-positive specimens. The tandem repeat combined with the enhanced Centers for Disease Control and Prevention typing system resulted in increased discrimination and should be useful for molecular epidemiologic studies on syphilis especially in outbreaks and among men who have sex with men.

Multilocus Sequence Typing of Treponema pallidum subsp. pallidum in Cuba From 2012 to 2017

BACKGROUND

The increased prevalence of syphilis in Cuba prompted us to map the circulating Treponema pallidum subsp. pallidum allelic profiles in this geographic region.

METHODS

Samples were collected from 2012 to 2017, from 83 male patients with ulcers or skin lesions, and were examined using multilocus sequence typing. Additionally, we analyzed the 23S rDNA and 16S rDNA regions for the presence of possible mutations leading to macrolide and tetracycline resistance.

RESULTS

Among 94% of fully typed strains, we found 7 different allelic profiles, of which 4 had not been previously described. More than 87% of patients were infected with the T. pallidum SS14-like group and only 8.2% with T. pallidum Nichols-like group. As in other countries, the 1.3.1 allelic profile (ie, SS14-like) was the most common. In addition, 1 of the newly described allelic profiles represents T. pallidum strains that arose by recombination events between members of different T. pallidum subgroups. More than 90% of patients were infected with treponemes harboring the A2058G mutation. However, we found no potential tetracycline-resistant T. pallidum mutations.

CONCLUSIONS

Our results suggest that, in Cuba, tetracycline antibiotics could be used to treat syphilis in penicillin-allergic patients instead of macrolides.

Successful isolation of Treponema pallidum strains from patients' cryopreserved ulcer exudate using the rabbit model

Clinical isolates of Treponema pallidum subspecies pallidum (T. pallidum) would facilitate study of prevalent strains. We describe the first successful rabbit propagation of T. pallidum from cryopreserved ulcer specimens. Fresh ulcer exudates were collected and cryopreserved with consent from syphilis-diagnosed patients (N = 8). Each of eight age-matched adult male rabbits were later inoculated with a thawed specimen, with two rabbits receiving 1.3 ml intratesticularly (IT), and six receiving 0.6 ml intravenously (IV) and IT. Monitoring of serology, blood PCR and orchitis showed that T. pallidum grew in 2/8 rabbits that were inoculated IV and IT with either a penile primary lesion specimen (CDC-SF003) or a perianal secondary lesion specimen (CDC-SF007). Rabbit CDC-SF003 was seroreactive by T. pallidum Particle Agglutination (TP-PA) and Rapid Plasma Reagin (RPR) testing, PCR+, and showed orchitis by week 6. Euthanasia was performed in week 7, with treponemal growth in the testes confirmed and quantified by qPCR and darkfield microscopy (DF). Serial passage of the extract in a second age-matched rabbit also yielded treponemes. Similarly, rabbit CDC-SF007 showed negligible orchitis, but was seroreactive and PCR+ by week 4 and euthanized in week 6 to yield T. pallidum, which was further propagated by second passage. Using the 4-component molecular typing system for syphilis, 3 propagated strains (CDC-SF003, CDC-SF007, CDC-SF008) were typed as 14d9f, 14d9g, and 14d10c, respectively. All 3 isolates including strain CDC-SF011, which was not successfully propagated, had the A2058G mutation associated with azithromycin resistance. Our results show that immediate cryopreservation of syphilitic ulcer exudate can maintain T. pallidum viability for rabbit propagation.

A comparison of genotyping tool in Treponema pallidum: Review and meta-analysis

BACKGROUND

To decipher the molecular epidemiology of the Treponema pallidum subspecies, pallidum, researchers have developed different molecular typing schemes which identify strains type from clinical specimens. However, the results of these studies show remarkable diversity.

METHODS

We searched for literature in PubMed, MEDLINE, Web of Sciences, and OVID from January 1998 to January 2019, in order to compare the efficiency of typing schemes using published evidence for systematic reviews and meta-analyses.

RESULTS

From the 43 studies included, the overall typing efficiency of Treponema pallidum was 71.4% (95% CI: 63.2-78.9%). Subgroup analyses indicated that the typing efficiency of CDC-typing (CDCT, 68.2%, 95% CI: 53.6-81.2%) was worse than those of enhanced CDC-typing (ECDCT, 72.3%, 95% CI: 60-83.1%), CDC-rspA (81.6%, 95% CI: 76.1-86.6%), multi-locus sequence typing (MLST, 67.1%, 95% CI: 61.1-72.7), and sequencing-based molecular typing (SBMT, 71.6%, 95% CI: 50-89.2%). A limitation of this review is that the studies included employed different criteria to collect and investigate samples of Treponema pallidum, which could contribute to heterogeneity.

CONCLUSIONS

This analysis suggests that CDCT is an inferior scheme in molecular typing, the discriminatory power was very similar for ECDCT and SBMT. Other factors contributing to the heterogeneity between typing studies warrants further study.

Genomic epidemiology of syphilis reveals independent emergence of macrolide resistance across multiple circulating lineages

Syphilis is a sexually transmitted infection caused by Treponema pallidum subspecies pallidum and may lead to severe complications. Recent years have seen striking increases in syphilis in many countries. Previous analyses have suggested one lineage of syphilis, SS14, may have expanded recently, indicating emergence of a single pandemic azithromycin-resistant cluster. Here we use direct sequencing of T. pallidum combined with phylogenomic analyses to show that both SS14- and Nichols-lineages are simultaneously circulating in clinically relevant populations in multiple countries. We correlate the appearance of genotypic macrolide resistance with multiple independently evolved SS14 sub-lineages and show that genotypically resistant and sensitive sub-lineages are spreading contemporaneously. These findings inform our understanding of the current syphilis epidemic by demonstrating how macrolide resistance evolves in Treponema subspecies and provide a warning on broader issues of antimicrobial resistance.

Comparison of Treponema pallidum genomes for the prediction of resistance genes

Syphilis is a sexually transmitted infection caused by Treponema pallidum, which is highly prevalent in several countries, including Brazil. The use of bioinformatics' tools for the identification of resistance genes is an important practice for the study of microorganisms, such as T. pallidum. In this study, the complete genomes of 43 strains of T. pallidum, isolated from different countries, were analyzed. A total of 41,514 sequences were obtained, and compared against prokaryote resistance gene databases using BLASTn, BLASTx and RGI for gene alignment and prediction. From the alignments, it was possible to identify antibiotic resistance genes for each strain. The genes identified in each comparison were grouped according to the antibiotic category in which they show resistance to. The antibiotic-resistant genes related to drugs used to treat syphilis were grouped separately. The in silico tools used have shown to be effective in identifying resistance genes in genomes of T. pallidum strains. Due to the lack of research and accurate information regarding the antibiotic resistance genes in T. pallidum, this study serves as a basis for studies in molecular biology whose aim is the identification of these genes, besides being a reference to help in the control and treatment of this infection.

MLST typing of Treponema pallidum subsp. pallidum in the Czech Republic during 2004-2017: Clinical isolates belonged to 25 allelic profiles and harbored 8 novel allelic variants

A recently introduced Multilocus Sequence Typing scheme for Treponema pallidum subsp. pallidum was applied to clinical samples collected from 2004 to 2017 from the two largest cities (Prague and Brno) in the Czech Republic. Altogether, a total of 675 samples were tested in this study and 281 of them were found PCR-positive for treponemal DNA and typeable. Most of the typed samples (n = 281) were swabs from primary or secondary syphilis lesions (n = 231), and only a minority were whole blood or tissue samples (n = 50). Swab samples from patients with rapid plasma regain (RPR) values of 1–1024 were more frequently PCR-positive (84.6%) compared to samples from patients with non-reactive RPR test (46.5%; p-value = 0.0001). Out of 281 typeable samples, 136 were fully-typed at all TP0136, TP0548, and TP0705 loci. Among the fully and partially typed samples, 25 different allelic profiles were identified. Altogether, eight novel allelic variants were found among fully (n = 5) and partially (n = 3) typed samples. The distribution of TPA allelic profiles identified in the Czech Republic from 2004 to 2017 revealed a dynamic character with allelic profiles disappearing and emerging over time. While the number of samples with the A2058G mutation was seen to increase (86.7% in 2016/2017), the number of samples harboring the A2059G mutation was found to have decreased over time (3.3% in 2016/2017). In addition, we found several allelic profile associations with macrolide resistance or susceptibility, the gender of patients, as well as patient residence.

Enhanced Molecular Typing of Treponema pallidum subspecies pallidum Strains From 4 Italian Hospitals Shows Geographical Differences in Strain Type Heterogeneity, Widespread Resistance to Macrolides, and Lack of Mutations Associated With Doxycycline Resistance

BACKGROUND

Although syphilis rates have been relatively high in Italy for more than 15 years, no data on the molecular types of Treponema pallidum subspecies pallidum circulating in this country are yet available. Likewise, no data on how widespread is resistance to macrolide or tetracycline antibiotics in these strains exist. Such data would, however, promote comprehensive studies on the molecular epidemiology of syphilis infections in Italy and inform future interventions aiming at syphilis control in this and other European countries.

GOALS AND STUDY DESIGN

Swabs from oral, genital, cutaneous, or anal lesions were obtained from 60 syphilis patients attending dermatology clinics in Milan, Turin, Genoa, and Bologna. Molecular typing of T. pallidum DNA was performed to provide a snapshot of the genetic diversity of strains circulating in Northern Italy. Samples were also screened for mutations conferring resistance to macrolides and tetracyclines.

RESULTS

T. pallidum DNA was detected in 88.3% (53/60) of the specimens analyzed. Complete and partial T. pallidum typing data were obtained for 77.3% (41/53) and 15.0% (8/53) of samples, respectively, whereas 4 samples could not be typed despite T. pallidum DNA being detected. The highest strain type heterogeneity was seen in samples from Bologna and Milan, followed by Genoa. Minimal diversity was detected in samples from Turin, despite the highest number of typeable samples collected there. Resistance to macrolides was detected in 94.3% (50/53) of the strains, but no known mutations associated with tetracycline resistance were found.

CONCLUSIONS

Genetic diversity among T. pallidum strains circulating in Northern Italy varies significantly among geographical areas regardless of physical distance. Resistance to macrolides is widespread.

Topical treatment with gallium maltolate reduces Treponema pallidum subsp. pertenue burden in primary experimental lesions in a rabbit model of yaws

Background

Gallium is a semi-metallic element known since the 1930s to have antimicrobial activity. This activity stems primarily from gallium's ability to mimic trivalent iron and disrupt specific Fe(III)-dependent pathways, particularly DNA synthesis (due to inhibition of ribonucleotide reductase). Because of its novel mechanism of action, gallium is currently being investigated as a new antibacterial agent, particularly in light of the increasing resistance of many pathogenic bacteria to existing antibiotics. Gallium maltolate (GaM) is being developed as an orally and topically administrable form of gallium. Yaws is a neglected tropical disease affecting mainly the skin and skeletal system of children in underprivileged settings. It is currently the object of a WHO-promoted eradication campaign using mass administration of the macrolide azithromycin, an antibiotic to which the yaws agent Treponema pallidum subsp. pertenue has slowly begun to develop genetic resistance.

Methods

Because yaws transmission is mainly due to direct skin contact with an infectious skin lesion, we evaluated the treponemicidal activity of GaM applied topically to skin lesions in a rabbit model of yaws. Treatment efficacy was evaluated by measuring lesion diameter, treponemal burden in lesion aspirates as determined by dark field microscopy and amplification of treponemal RNA, serology, and immunohistochemistry of biopsied tissue samples.

Results

Our results show that topical GaM was effective in reducing treponemal burden in yaws experimental lesions, particularly when applied at the first sign of lesion appearance but, as expected, did not prevent pathogen dissemination.

Conclusion

Early administration of GaM to yaws lesions could reduce the infectivity of the lesions and thus yaws transmission, potentially contributing to current and future yaws control campaigns.

Yaws is a neglected tropical disease affecting children in underprivileged countries, transmitted through direct skin contact with an active lesion. This infection, although rarely fatal, can lead to disfigurement and serious disability. The World Health Organization is currently conducting a yaws eradication effort that employs mass administration of azithromycin, an antibiotic against which the yaws pathogen has slowly begun to develop genetic resistance. Because this phenomenon has the potential to undermine the eradication effort, we investigated the antimicrobial activity of gallium maltolate, which has a novel mechanism of action, against the yaws pathogen. Our initial results show that topical application of gallium maltolate has significant treponemicidal activity, and suggest that this compound might find an application in the effort to eradicate yaws. Future studies will evaluate whether oral administration of gallium maltolate is as effective as the antibiotics currently approved for yaws treatment to clear systemic infection.

Prevalence of macrolide resistance in Treponema pallidum is associated with macrolide consumption

We hypothesized that the large global variations in the prevalence of macrolide resistance in Treponema pallidum are related to differences in population-level macrolide consumption. The hypothesis was tested by, at a country-level, regressing the peak prevalence of macrolide resistance against the national macrolide consumption in the year prior to this, controlling for the year of the resistance prevalence estimate. A strong association was found between the per capita consumption of macrolides and macrolide resistance (coefficient 0.7, 95 % confidence interval 0.2-0.12, P=0.009).

Advances in the Treatment of Yaws

Yaws is one of the three endemic treponematoses and is recognised by the World Health Organization as a neglected tropical disease. Yaws is currently reported in 15 countries in the Pacific, South-East Asia, West and Central Africa, predominantly affects children, and results in destructive lesions of the skin and soft tissues. For most of the twentieth century penicillin-based treatment was the standard of care and resistance to penicillin has still not been described. Recently, oral azithromycin has been shown to be an effective treatment for yaws, facilitating renewed yaws eradication efforts. Resistance to azithromycin is an emerging threat and close surveillance will be required as yaws eradication efforts are scaled up globally.

Multi-locus sequence typing of Treponema pallidum subsp. pallidum present in clinical samples from France: Infecting treponemes are genetically diverse and belong to 18 allelic profiles

Treponema pallidum subsp. pallidum, the causative agent of sexually transmitted syphilis, detected in clinical samples from France, was subjected to molecular typing using the recently developed Multilocus Sequence Typing system. The samples (n = 133) used in this study were collected from 2010-2016 from patients with diagnosed primary or secondary syphilis attending outpatient centers or hospitals in several locations in France. Altogether, 18 different allelic profiles were found among the fully typed samples (n = 112). There were five allelic variants identified for TP0136, 12 for TP0548, and eight for TP0705. Out of the identified alleles, one, seven, and three novel alleles were identified in TP0136, TP0548, and TP0705, respectively. Partial allelic profiles were obtained from 6 samples. The majority of samples (n = 110) belonged to the SS14-like cluster of TPA isolates while 7 clustered with Nichols-like isolates. Patients infected with Nichols-like samples were more often older (p = 0.041) and more often diagnosed with secondary syphilis (p = 0.033) compared to patients infected with SS14-like samples. In addition, macrolide resistance caused by the A2058G mutation was found to be associated with allelic profile 1.3.1 or with strains belonging to the 1.3.1 lineage (p<0.001). The genetic diversity among TPA strains infecting the European population was surprisingly high, which suggests that additional studies are needed to reveal the full genetic diversity of TPA pathogens infecting humans.

Re-emergence of yaws after single mass azithromycin treatment followed by targeted treatment: a longitudinal study

BACKGROUND

Yaws is a substantial cause of chronic disfiguring ulcers in children in at least 14 countries in the tropics. WHO's newly adopted strategy for yaws eradication uses a single round of mass azithromycin treatment followed by targeted treatment programmes, and data from pilot studies have shown a short-term significant reduction of yaws. We assessed the long-term efficacy of the WHO strategy for yaws eradication.

METHODS

Between April 15, 2013, and Oct 24, 2016, we did a longitudinal study on a Papua New Guinea island (Lihir; 16 092 population) in which yaws was endemic. In the initial study, the participants were followed for 12 months; in this extended follow-up study, clinical, serological, and PCR surveys were continued every 6 months for 42 months. We used genotyping and travel history to identify importation events. Active yaws confirmed by PCR specific for Treponema pallidum was the primary outcome indicator. The study is registered with ClinicalTrials.gov, number NCT01955252.

FINDINGS

Mass azithromycin treatment (coverage rate of 84%) followed by targeted treatment programmes reduced the prevalence of active yaws from 1·8% to a minimum of 0·1% at 18 months (difference from baseline -1·7%, 95% CI, -1·9 to -1·4; p<0·0001), but the infection began to re-emerge after 24 months with a significant increase to 0·4% at 42 months (difference from 18 months 0·3%, 95% CI 0·1 to 0·4; p<0·0001). At each timepoint after baseline, more than 70% of the total community burden of yaws was found in individuals who had not had the mass treatment or as new infections in non-travelling residents. At months 36 and 42, five cases of active yaws, all from the same village, showed clinical failure following azithromycin treatment, with PCR-detected mutations in the 23S ribosomal RNA genes conferring resistance to azithromycin. A sustained decrease in the prevalence of high-titre latent yaws from 13·7% to <1·5% in asymptomatic children aged 1-5 years old and of genetic diversity of yaws strains from 0·139 to less than 0·046 between months 24 and 42 indicated a reduction in transmission of infection.

INTERPRETATION

The implementation of the WHO strategy did not, in the long-term, achieve elimination in a high-endemic community mainly due to the individuals who were absent at the time of mass treatment in whom yaws reactivated; repeated mass treatment might be necessary to eliminate yaws. To our knowledge, this is the first report of the emergence of azithromycin-resistant T p pertenue and spread within one village. Communities' surveillance should be strengthened to detect any possible treatment failure and biological markers of resistance.

FUNDING

ISDIN laboratories, Newcrest Mining Limited, and US Public Health Service National Institutes of Health.

Genetics of human and animal uncultivable treponemal pathogens

Treponema pallidum is an uncultivable bacterium and the causative agent of syphilis (subsp. pallidum [TPA]), human yaws (subsp. pertenue [TPE]), and bejel (subsp. endemicum). Several species of nonhuman primates in Africa are infected by treponemes genetically undistinguishable from known human TPE strains. Besides Treponema pallidum, the equally uncultivable Treponema carateum causes pinta in humans. In lagomorphs, Treponema paraluisleporidarum ecovar Cuniculus and ecovar Lepus are the causative agents of rabbit and hare syphilis, respectively. All uncultivable pathogenic treponemes harbor a relatively small chromosome (1.1334-1.1405 Mbp) and show gene synteny with minimal genetic differences (>98% identity at the DNA level) between subspecies and species. While uncultivable pathogenic treponemes contain a highly conserved core genome, there are a number of highly variable and/or recombinant chromosomal loci. This is also reflected in the occurrence of intrastrain heterogeneity (genetic diversity within an infecting bacterial population). Molecular differences at several different chromosomal loci identified among TPA strains or isolates have been used for molecular typing and the epidemiological characterization of syphilis isolates. This review summarizes genome structure of uncultivable pathogenic treponemes including genetically variable regions.

An Update on the Global Epidemiology of Syphilis

PURPOSE OF REVIEW

Syphilis continues to cause morbidity and mortality worldwide. While syphilis infection is easily identifiable and treatable, rates of syphilis infection continue to increase among select populations in high-income countries and remain at endemic levels in low- and middle-income counties.

RECENT FINDINGS

World Health Organization recommended strategies have led to the dual elimination of mother-to-child transmission of syphilis and HIV in several countries, however outbreaks among select populations need to be adequately addressed.

SUMMARY

Continued vigilance and investment is needed to address syphilis worldwide. The epidemiology of syphilis differs in high-income and low- and middle-income counties.

Molecular Typing of Syphilis-Causing Strains Among Human Immunodeficiency Virus-Positive Patients in Antwerp, Belgium

Centers for Disease Control and Prevention and sequencing-based treponeme typing was used to analyze 72 blood samples, collected from human immunodeficiency virus and syphilis co-infected patients during 2014 to 2015 in Antwerp, Belgium. Twenty-nine (40.3%) isolates were polymerase chain reaction positive for Treponema pallidum, and all tested were macrolide-resistant. Four genotypes were identified by sequencing-based typing including two new genotypes, U4NR8 and SU9R8, whereas enhanced Centers for Disease Control and Prevention typing revealed 7 subtypes.

Treponema pallidum pallidum Genotypes and Macrolide Resistance Status in Syphilitic Lesions among Patients at 2 Sexually Transmitted Infection Clinics in Lima, Peru

We report the circulating genotypes and the frequency of macrolide-resistance patterns among Treponema pallidum pallidum DNA isolated from syphilitic lesions from patients who attended 2 sexual health clinics in Lima, Peru. We implemented and used a molecular typing scheme to describe local T. pallidum pallidum strains. Among 14 specimens, subtype 14d/f was the most prevalent strain in 7 fully typed T. pallidum DNA specimens obtained from men who have sex with men and transgender women presenting with chancre-like lesions. No macrolide-resistance mutations were found in T. pallidum DNA from 10 lesions.

First Report of the 23S rRNA Gene A2058G Point Mutation Associated With Macrolide Resistance in Treponema pallidum From Syphilis Patients in Cuba

This study aimed to assess the presence of macrolide-resistant Treponema pallidum subtypes in Havana, Cuba. Samples from 41 syphilis patients were tested for T. pallidum 23S rRNA gene mutations. Twenty-five patients (61%) harbored T. pallidum with the A2058G mutation, which was present in all 8 subtypes that were identified. The A2059G mutation was not detected.

Molecular Subtyping and Surveillance of Resistance Genes In Treponema pallidum DNA From Patients With Secondary and Latent Syphilis in Hunan, China

BACKGROUND

Over the past decade, the incidence of syphilis and widespread macrolide resistance in its etiological agent, Treponema pallidum subsp. pallidum, have become a major health concern across countries, including China. Regional trends in subtypes and antibiotic resistance can be monitored effectively by molecular surveillance programs. In this study, whole blood samples were used to assess circulating T. pallidum strains collected from various regions of Hunan, China, between 2013 and 2015.

METHODS

Traditional polymerase chain reaction, targeting polA, tpp47, bmp, and tp0319 genes, was used as preliminary screening assay. About 455 polymerase chain reaction-positive specimens were obtained from 2253 whole blood samples of patients with secondary or latent syphilis. Molecular subtyping was performed using a Centers for Disease Control and Prevention-based typing method combined with an analysis of the variable region of tp0548 gene. Resistance to macrolides was analyzed by examining point mutations in 23S rRNA, and the presence of the G1058C point mutation within 16S rRNA associated with decreased susceptibility to doxycycline was assessed.

RESULTS

Circulating T. pallidum strains were resolved into 32 subtypes, among which subtype 14d/f was predominant. A2059G mutation in 23S rRNA, and the G1058C mutation in 16S rRNA was absent, but the prevalence of A2058G mutation in 23S rRNA was 97.5%.

CONCLUSIONS

We found that it is possible to use whole blood to evaluate molecular subtypes and monitor antibiotic resistance in circulating T. pallidum strains, especially when chancres are absent. High frequency of macrolide-resistant T. pallidum indicates that macrolide antibiotics, such as azithromycin, should be avoided as a treatment option for syphilis in Hunan, China.

Detection and identification of azithromycin resistance mutations on

Background: Azithromycin-resistant strains of Treponema pallidum is associated with the mutation of 23S rRNA gene of T. pallidum. Although these strains are now prevalent in many countries, there is no laboratory test kit to detect and identify these mutations. Thus, in this study we developed a nested multiplex polymerase chain reaction (PCR) to detect and identify A2058G and A2059G mutations in 23S rRNA gene.Methods: Three primer sets were designed for nested PCR reactions. To obtain maximum PCR reaction, all parameters were optimized. The specificity of the primer sets was evaluated towards some microorganisms. A sensitivity test was conducted to get detection limit of deoxyribonucleic acid (DNA). Forty-five whole blood specimens were tested by PCR, and positive results were confirmed by the DNA sequencing.Results: The assay could detect at least 4,400 DNA copy number and showed no cross reaction with other microorganisms used in the specificity test. A total 13 of 45 whole blood specimens were PCR positive for T. pallidum, and no single mutations (either A2058G or A2059G) were detected. Two positive specimens were confirmed by the DNA sequencing and showed no mutation.Conclusion: Nested multiplex PCR developed in this study showed a specific and sensitive test for the detection and identification of A2058G and/or A2059G mutations of 23S rRNA T. pallidum gene.

Molecular typing of Treponema pallidum isolates from Buenos Aires, Argentina: Frequent Nichols-like isolates and low levels of macrolide resistance

A total of 54 clinical samples, including genital lesion swabs, whole blood and cerebrospinal fluid from patients diagnosed with syphilis were collected in 2006 and in 2013 in Buenos Aires, Argentina. Treponemal DNA was detected in 43 of the analyzed samples (79.6%) and further analyzed using Sequencing-based molecular typing (SBMT) and Enhanced CDC-typing (ECDCT). By SBMT, 10 different Treponema pallidum subsp. pallidum (TPA) genotypes were found, of which six were related to the TPA SS14 strain, and four to the TPA Nichols strain. The 23S rRNA gene was amplified in samples isolated from 42 patients, and in six of them (14.3%), either the A2058G (four patients, 9.5%) or the A2059G (two patients, 4.8%) mutations were found. In addition to Taiwan, Madagascar and Peru, Argentina is another country where the prevalence of Nichols-like isolates (26.8%) is greater than 10%.

A Single Dose Oral Azithromycin versus Intramuscular Benzathine Penicillin for the Treatment of Yaws-A Randomized Non Inferiority Trial in Ghana

Background

Yaws is a treponemal infection that was almost eradicated fifty years ago; however, the disease has re-emerged in a number of countries including Ghana. A single-dose of intramuscular benzathine penicillin has been the mainstay of treatment for yaws. However, intramuscular injections are painful and pose safety and logistical constraints in the poor areas where yaws occurs. A single center randomized control trial (RCT) carried out in Papua New Guinea in 2012 demonstrated the efficacy of a single-dose of oral azithromycin for the treatment of yaws. In this study, we also compared the efficacy of a single oral dose of azithromycin as an alternative to intramuscular benzathine penicillin for the treatment of the disease in another geographic setting.

Methodology

We conducted an open-label, randomized non-inferiority trial in three neighboring yaws-endemic districts in Southern Ghana. Children aged 1–15 years with yaws lesions were assigned to receive either 30mg/kg of oral azithromycin or 50,000 units/kg of intramuscular benzathine penicillin. The primary end point was clinical cure rate, defined as a complete or partial resolution of lesions 3 weeks after treatment. The secondary endpoint was serological cure, defined as at least a 4-fold decline in baseline RPR titre 6 months after treatment. Non- inferiority of azithromycin treatment was determined if the upper bound limit of a 2 sided 95% CI was less than 10%.

Findings

The mean age of participants was 9.5 years (S.D.3.1, range: 1–15 years), 247(70%) were males. The clinical cure rates were 98.2% (95% CI: 96.2–100) in the azithromycin group and 96.9% (95% CI: 94.1–99.6) in the benzathine penicillin group. The serological cure rates at 6 months were 57.4% (95% CI: 49.9–64.9) in the azithromycin group and 49.1% (95% CI: 41.2–56.9) in the benzathine penicillin group, thus achieving the specified criteria for non-inferiority.

Conclusions

A single oral dose of azithromycin, at a dosage of 30mg/kg, was non-inferior to a single dose of intramuscular benzathine penicillin for the treatment of early yaws among Ghanaian patients, and provides additional support for the WHO policy for use of oral azithromycin for the eradication of yaws in resource-poor settings.

Trial Registration

Pan African Clinical Trials Registry PACTR2013030005181http://www.pactr.org/

Yaws is a tropical infection caused by a bacterium closely related to that which causes syphilis. It is transmitted from person to person through skin to skin contact and often causes papillomatous and ulcerative skin lesions, usually in young children. Without treatment, it can lead to deformities and disabilities. In the past, treatment of cases and their contacts and mass treatment of whole communities has been conducted using single doses of long acting penicillin. This treatment is inexpensive and does not pose a problem with adherence. However, the injections are painful and make it difficult to gain the cooperation of children. In addition, it requires trained health workers to safely administer treatment in poor-resource settings where yaws commonly occurs. In this study one group of children aged 1–15 years with clinically and serologically confirmed yaws received the standard treatment of a single injection of benzathine penicillin. A second group of children were treated with a single dose of oral azithromycin. The children were followed up at 3 weeks to assess healing of lesions, and at 3 and 6 months respectively to monitor serological indicators of infection. Our conclusion is that single dose oral azithromycin is as effective as a single injection of benzathine penicillin for the treatment of early yaws in Ghana and confirms the findings of a previous study undertaken in Papua New Guinea.

Origin of modern syphilis and emergence of a pandemic Treponema pallidum cluster

The abrupt onslaught of the syphilis pandemic that started in the late fifteenth century established this devastating infectious disease as one of the most feared in human history¹. Surprisingly, despite the availability of effective antibiotic treatment since the mid-twentieth century, this bacterial infection, which is caused by Treponema pallidum subsp. pallidum (TPA), has been re-emerging globally in the last few decades with an estimated 10.6 million cases in 2008 (ref. 2). Although resistance to penicillin has not yet been identified, an increasing number of strains fail to respond to the second-line antibiotic azithromycin³. Little is known about the genetic patterns in current infections or the evolutionary origins of the disease due to the low quantities of treponemal DNA in clinical samples and difficulties in cultivating the pathogen⁴. Here, we used DNA capture and whole-genome sequencing to successfully interrogate genome-wide variation from syphilis patient specimens, combined with laboratory samples of TPA and two other subspecies. Phylogenetic comparisons based on the sequenced genomes indicate that the TPA strains examined share a common ancestor after the fifteenth century, within the early modern era. Moreover, most contemporary strains are azithromycin-resistant and are members of a globally dominant cluster, named here as SS14-Ω. The cluster diversified from a common ancestor in the mid-twentieth century subsequent to the discovery of antibiotics. Its recent phylogenetic divergence and global presence point to the emergence of a pandemic strain cluster.

Macrolide Resistance in Treponema pallidum Correlates With 23S rDNA Mutations in Recently Isolated Clinical Strains

BACKGROUND

High rates of 23S rDNA mutations implicated in macrolide resistance have been identified in Treponema pallidum samples from syphilis patients in many countries. Nonetheless, some clinicians have been reluctant to abandon azithromycin as a treatment for syphilis, citing the lack of a causal association between these mutations and clinical evidence of drug resistance. Although azithromycin resistance has been demonstrated in vivo for the historical Street 14 strain, no recent T. pallidum isolates have been tested. We used the well-established rabbit model of syphilis to determine the in vivo efficacy of azithromycin against 23S rDNA mutant strains collected in 2004 to 2005 from patients with syphilis in Seattle, Wash.

METHODS

Groups of 9 rabbits were each infected with a strain containing 23S rDNA mutation A2058G (strains UW074B, UW189B, UW391B) or A2059G (strains UW228B, UW254B, and UW330B), or with 1 wild type strain (Chicago, Bal 3, and Mexico A). After documentation of infection, 3 animals per strain were treated with azithromycin, 3 were treated with benzathine penicillin G, and 3 served as untreated control groups. Treatment efficacy was documented by darkfield microscopic evidence of T. pallidum, serological response, and rabbit infectivity test.

RESULTS

Azithromycin uniformly failed to cure rabbits infected with strains harboring either 23S rDNA mutation, although benzathine penicillin G was effective. Infections caused by wild type strains were successfully treated by either azithromycin or benzathine penicillin G.

CONCLUSIONS

A macrolide resistant phenotype was demonstrated for all strains harboring a 23S rDNA mutation, demonstrating that either A2058G or A2059G mutation confers in vivo drug resistance.

Syphilis: Re-emergence of an old foe

Syphilis is caused by infection with Treponema pallidum subsp. pallidum, a not-yet-cultivable spiral-shaped bacterium that is usually transmitted by sexual contact with an infected partner or by an infected pregnant woman to her fetus. There is no vaccine to prevent syphilis. Diagnosis and treatment of infected individuals and their contacts is key to syphilis control programs that also include sex education and promotion of condom use to prevent infection. Untreated syphilis can progress through four stages: primary (chancre, regional lymphadenopathy), secondary (disseminated skin eruptions, generalized lymphadenopathy), latent (decreased re-occurrence of secondary stage manifestations, absence of symptoms), and tertiary (gummas, cardiovascular syphilis and late neurological symptoms). The primary and secondary stages are the most infectious. WHO estimates that each year 11 million new cases of syphilis occur globally among adults aged 15-49 years. Syphilis has re-emerged in several regions including North America, Western Europe, China and Australia. Host-associated factors that drive the re-emergence and spread of syphilis include high-risk sexual activity, migration and travel, and economic and social changes that limit access to health care. Early, uncomplicated syphilis is curable with a single intramuscular injection of benzathine penicillin G (BPG), the first line drug for all stages of syphilis. Emergence of macrolide-resistant T. pallidum has essentially precluded the empirical use of azithromycin as a second-line drug for treatment of syphilis. Virulence attributes of T. pallidum are poorly understood. Genomic and proteomic studies have provided some new information concerning how this spirochete may evade host defense mechanisms to persist for long periods in the host.

Treponema pallidum Strain Types and Association with Macrolide Resistance in Sydney, Australia: New TP0548 Gene Types Identified

Strain typing of Treponema pallidum, using the three-target enhanced classification scheme, was performed with 191 samples obtained between 2004 and 2011 in Sydney, Australia. The most common strain type was 14d/g (92/191 samples [48%]). Two new TP0548 gene types were detected (m and n). Strain type was associated with macrolide resistance and possible acquisition outside Australia.

Macrolide Resistance in the Syphilis Spirochete, Treponema pallidum ssp. pallidum: Can We Also Expect Macrolide-Resistant Yaws Strains?

Treponema pallidum ssp. pallidum (TPA) causes over 10 million new cases of syphilis worldwide whereas T. pallidum ssp. pertenue (TPE), the causative agent of yaws, affects about 2.5 million people. Although penicillin remains the drug of choice in the treatment of syphilis, in penicillin-allergic patients, macrolides have been used in this indication since the 1950s. Failures of macrolides in syphilis treatment have been well documented in the literature and since 2000, there has been a dramatic increase in a number of clinical samples with macrolide-resistant TPA. Scarce data regarding the genetics of macrolide-resistant mutations in TPA suggest that although macrolide-resistance mutations have emerged independently several times, the increase in the proportion of TPA strains resistant to macrolides is mainly due to the spread of resistant strains, especially in developed countries. The emergence of macrolide resistance in TPA appears to require a two-step process including either A2058G or A2059G mutation in one copy of the 23S rRNA gene and a subsequent gene conversion unification of both rRNA genes. Given the enormous genetic similarity that was recently revealed between TPA and TPE strains, there is a low but reasonable risk of emergence and spread of macrolide-resistant yaws strains following azithromycin treatment.

Syphilis testing, typing, and treatment follow-up: a new era for an old disease

PURPOSE OF REVIEW

The past 15 years have seen a dramatic increase in syphilis diagnoses in several regions including China, North America, Western Europe and Australia. Worldwide, the disease remains prevalent, contributing to substantial adult morbidity and neonatal mortality. Testing and treatment strategies are largely informed by data from the early antibiotic era, but increasing use of molecular diagnostics and new screening strategies could improve the management of syphilis substantially.

RECENT FINDINGS

The review explores new testing strategies for syphilis, including the importance of screening test selection and advances in point-of-care diagnostics. It then examines molecular studies of Treponema pallidum, covering typing; macrolide resistance; association between genotype and phenotype and the use of PCR in testing and monitoring strategies.

SUMMARY

Clinicians should be aware of testing strategies employed by their laboratories to ensure optimal sensitivity and specificity. Locally available T. pallidum PCR assays may improve the diagnosis of early disease and inform antibiotic choice. Robust serologic follow-up is still required, but predictors of potential treatment failure, including PCR-measured bacterial load, have been identified. Re-treatment should be considered for patients in the serofast state. The publication of T. pallidum genomes would allow further and more detailed study of strains and disease pathogenesis.

Clinical and epidemiological characteristics of patients with early syphilis from three academic centres in Poland, Germany and Ireland: initial findings from the POETS study

OBJECTIVES

Syphilis recognition in HIV-positive patients has important implications. Initial data from this study, established in June 2012 to better understand the natural history of syphilis and treatment response, examine the characteristics of patients including sexual behaviour, rates of concurrent sexually transmitted infections (STI) and type of treatment given.

METHODS

Patients were recruited from Ireland, Poland and Germany. Data gathered included demographics, method of syphilis acquisition, stage of syphilis infection, HIV status, nadir and current CD4 counts and HIV viral suppression rates. Data were then subanalysed into HIV-positive and HIV-negative groups.

RESULTS

Of 175 patients recruited, 68% were HIV-positive and 86.3% were men who have sex with men. Most HIV-positive patients presented with secondary syphilis (55.7% vs 13.2%) (p=0.0001) while the majority of HIV-negative patients had primary syphilis noted at the time of recruitment (47.2% vs18.9%, p=0.0002). Approximately half of all patients had a HIV RNA viral load <40 copies/mL (55%). Previous syphilis infection occurred more frequently in HIV-positive than HIV-negative patients (p=0.0001). Concurrent STIs at the time of syphilis diagnosis were found in 26.8%, of whom 31 (25.4%) were HIV-positive (p=0.64). HIV-positive patients received doxycycline more frequently than their HIV-negative counterparts (33.6% vs 1.9%, p=0.0001) while HIV-negative patients were treated with long-acting penicillin in 88.7% of cases vs 58% of HIV-positive patients (p=0.0002).

CONCLUSIONS

A 40% rate of unsuppressed viraemia, high levels of STIs and varying treatment regimens represent a public health risk for Europe, suggesting the model of sexual healthcare delivery in HIV-positive patients requires further evaluation.

Syphilis: antibiotic treatment and resistance

Syphilis is a chronic, multi-stage infectious disease that is usually transmitted sexually by contact with an active lesion of a partner or congenitally from an infected pregnant woman to her fetus. Although syphilis is still endemic in many developing countries, it has re-emerged in several developed countries. The resurgence of syphilis is a major concern to global public health, particularly since the lesions of early syphilis increase the risk of acquisition and transmission of infection with human immunodeficiency virus (HIV). Because there is no vaccine to prevent syphilis, control is mainly dependent on the identification and treatment of infected individuals and their contacts with penicillin G, the first-line drug for all stages of syphilis. The emergence of clinically significant azithromycin resistance in Treponema pallidum subsp. pallidum, the syphilis agent, has resulted in treatment failures, thus precluding the routine use of this second-line drug. Information is presented here on the diagnosis and recommended antibiotic treatment of syphilis and the challenge of macrolide-resistant T. pallidum.

Jarisch-Herxheimer reaction among HIV-positive patients with early syphilis: azithromycin versus benzathine penicillin G therapy

Introduction

The Jarisch-Herxheimer reaction, a febrile inflammatory reaction that often occurs after the first dose of chemotherapy in spirochetal diseases, may result in deleterious effects to patients with neurosyphilis and to pregnant women. A single 2-g oral dose of azithromycin is an alternative treatment to benzathine penicillin G for early syphilis in areas with low macrolide resistance. With its potential anti-inflammatory activity, the impact of azithromycin on the incidence of the Jarisch-Herxheimer reaction in HIV-positive patients with early syphilis has rarely been investigated.

Methods

In HIV-positive patients with early syphilis, the Jarisch-Herxheimer reaction was prospectively investigated using the same data collection form in 119 patients who received benzathine penicillin G between 2007 and 2009 and 198 who received azithromycin between 2012 and 2013, when shortage of benzathine penicillin G occurred in Taiwan. Between 2012 and 2013, polymerase chain reaction (PCR) assay was performed to detect Treponema pallidum DNA in clinical specimens, and PCR restriction fragment length polymorphism of the 23S ribosomal RNA was performed to detect point mutations (2058G or A2059G) that are associated with macrolide resistance.

Results

The overall incidence of the Jarisch-Herxheimer reaction was significantly lower in patients receiving azithromycin than those receiving benzathine penicillin G (14.1% vs. 56.3%, p<0.001). The risk increased with higher rapid plasma reagin (RPR) titres (adjusted odds ratio [AOR] per 1-log₂ increase, 1.21; confidence interval [CI], 1.04–1.41), but decreased with prior penicillin therapy for syphilis (AOR, 0.37; 95% CI, 0.19–0.71) and azithromycin treatment (AOR, 0.15; 95% CI, 0.08–0.29). During the study period, 310 specimens were obtained from 198 patients with syphilis for PCR assays, from whom T. pallidum was identified in 76 patients, one of whom (1.3%) was found to be infected with T. pallidum harbouring the macrolide resistance mutation (A2058G). In subgroup analyses confined to the 75 patients infected with T. pallidum lacking resistance mutation, a statistically significantly lower risk for the Jarisch-Herxheimer reaction following azithromycin treatment was noted.

Conclusions

Treatment with azithromycin was associated with a lower risk for the Jarisch-Herxheimer reaction than that with benzathine penicillin G in HIV-positive patients with early syphilis. Previous benzathine penicillin G therapy for syphilis decreased the risk, whereas higher RPR titres increased the risk, for the reaction.

Molecular typing of Treponema pallidum in the Czech Republic during 2011 to 2013: increased prevalence of identified genotypes and of isolates with macrolide resistance

From January 2011 to December 2013, a total of 262 samples, from 188 patients suspected of having syphilis were tested for the presence of treponemal DNA by PCR amplification of five chromosomal loci, including the polA (TP0105), tmpC (TP0319), TP0136, TP0548, and 23S rRNA genes. Altogether, 146 samples from 103 patients were PCR positive for treponemal DNA. A set of 81 samples from 62 PCR-positive patients were typeable, and among them, nine different genotypes were identified. Compared to a previous study in the Czech Republic during 2004 to 2010, the number of genotypes detected among syphilis patients in a particular year increased to six in both 2012 and 2013, although they were not the same six. The proportion of macrolide-resistant clinical isolates in this 3-year study was 66.7%.