Multicentre surveillance of prevalence of the 23S rRNA A2058G and A2059G point mutations and molecular subtypes of Treponema pallidum in Taiwan, 2009-2013

Analysis of molecular subtypes and antibiotic resistance in Treponema pallidum isolates from blood donors in Khyber Pakhtunkhwa, Pakistan

Syphilis, caused by Treponema pallidum, is resurging globally. Molecular typing allows for the investigation of its epidemiology. In Pakistan and other nations, T. pallidum subsp. pallidum has developed widespread macrolide resistance in the past decade. A study at the Peshawar Regional Blood Centre from June 2020-June 2021 analyzed serum samples from 32,812 blood donors in Khyber Pakhtunkhwa, Pakistan, to assess circulating T. pallidum strains and antibiotic resistance. Blood samples were initially screened for T. pallidum antibodies using a chemiluminescent microparticle immunoassay (CMIA). CMIA-reactive samples underwent polymerase chain reaction (PCR) targeted the polA, tpp47, bmp, and tp0319 genes. PCR-positive samples were further analyzed for molecular subtyping using a CDC-developed procedure and tp0548 gene examination. All PCR-positive samples were analyzed for the presence of point mutations A2058G and A2059G in 23S rRNA, as well as the G1058C mutation in 16S rRNA. These mutations are known to impart antimicrobial resistance to macrolides and doxycycline, respectively. Out of 32,812 serum samples, 272 (0.83%) were CMIA-reactive, with 46 being PCR-positive. Nine T. pallidum subtypes were identified, predominantly 14d/f. The A2058G mutation in 23S rRNA was found in 78% of cases, while G1058C in 16S rRNA and A2059G in 23S rRNA were absent. The research found donor blood useful for assessing T. pallidum molecular subtypes and antibiotic resistance, especially when chancres are not present. The prevalent subtype was 14d/f (51.85%), and the high macrolide resistance of 36 (78%) indicates caution in using macrolides for syphilis treatment in Khyber Pakhtunkhwa, Pakistan.

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

Introduction

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

Methods

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

Results

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

Conclusion

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

Supplementary Information

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

Genotyping of Treponema pallidum in Cuba (2018-2019): Increased Circulation of Recombinant Genotype and No New Treponema pallidum Subspecies endemicum Infection Among Syphilis Patients

OBJECTIVES

This study aimed to determine the allelic profiles of Treponema pallidum in patients confirmed with syphilis in Cuba (2018-2019) and to explore mutations leading to macrolide and tetracycline resistance.

METHODS

Multilocus sequence typing and polymerase chain reaction of rrn loci (23S and 16S rDNA), followed by Sanger sequencing, were used to define the allelic profile of TPA and resistance mutations, respectively.

RESULTS

Allelic profile 1.3.1 and the recombinant profile were identified, with 15.7.3 having an increased frequency. We did not detect the presence of the T. pallidum subspecies endemicum among syphilis patients, as in previous reports. A high frequency of macrolide-resistant strains and the absence of mutations potentially causing tetracycline resistance were found.

CONCLUSIONS

Understanding the current status of treponemal infection in Cuban patients provides insights into the syphilis epidemiology.

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.

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.

Molecular Typing and Macrolide Resistance of Syphilis Cases in Manitoba, Canada, From 2012 to 2016

BACKGROUND

The province of Manitoba, Canada, with a population of approximately 1.3 million, has been experiencing increased incidence of syphilis cases since 2015. In this study, we examined the detection of Treponema pallidum DNA in 354 clinical samples from 2012 to 2016, and determined molecular types and mutations conferring resistance to azithromycin in the polymerase chain reaction (PCR)-positive samples.

METHODS

T. pallidum DNA detection was done by PCR amplification of tpp47, bmp, and polA genes. Syphilis serology results were reviewed for the PCR-positive cases. Molecular typing of syphilis strains was done by analysis of the T, pallidum arp, tpr, and tp0548 gene targets as well as partial sequencing of the 23S rRNA gene for azithromycin resistance.

RESULTS

Of the 354 samples tested, 74 individual cases were PCR positive. A result from the treponemal antibody chemiluminescent microparticle immunoassay test was positive in 72 of these cases and that from the Venereal Disease Research Laboratory testing was positive in 66. Mutations conferring resistance to azithromycin were found in all 74 PCR-positive samples. Molecular typing was completed on 57 PCR-positive samples, and 12 molecular types were identified with 14d/g found in 63.2%. Increased strain diversity was observed with 8 molecular types detected in 2016, whereas only 2 to 3 types were found in 2012 to 2014. A patient with 2 episodes of infection 9 months apart caused by different molecular strain types was also identified.

CONCLUSIONS

The finding of an increase in genetic diversity in the strains in this study and an increase in macrolide resistance compared with previous Canadian reports highlighted the need for continued surveillance including strain characterization.

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.

Gene subtype analysis of Treponema pallidum for drug resistance to azithromycin

Azithromycin has been widely used for the treatment of Treponema pallidum. However, the drug resistance of T. pallidum for azithromycin is currently increasing. The aim of the present study was to analyze the association between gene subtypes of T. pallidum and drug resistance for azithromycin. The gene subtypes of T. pallidum were assayed by a polymerase chain reaction technique. Drug resistance of T. pallidum was analyzed using an antimicrobial susceptibility test. The results demonstrated that gene type tpr presented higher drug resistance compared with arp and tp0548 gene types of T. pallidum. Gene type tpr was identified as eight gene subtypes (14a/f, 14e/f, 12e/f, 12d/f, 6d/f, 11d/f, 14j/f and 8d/f) among 324 cases. It was identified that 23S rRNA A2058G mutation was observed in gene subtypes 14a/f, 14e/f and 12e/f. A2059G mutation occurred in the gene subtypes 8d/f, 12d/f, 6d/f, 11d/f and 14j/f. The proportions of azithromycin-resistant genotypes harboring either the A2058G or the A2059G mutation among the T. pallidum strains were 34.2 and 65.8%, respectively. The antimicrobial susceptibility test demonstrated that A2059G mutations exhibited a higher drug resistance for azithromycin compared with A2058G mutations. In conclusion, these results indicate that azithromycin resistance in T. pallidum is associated with gene subtype, which may contribute to the treatment of T. pallidum.

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.

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.

Whole genome sequence of the Treponema pallidum subsp. pallidum strain Amoy: An Asian isolate highly similar to SS14

Treponema pallidum ssp. pallidum (T. pallidum), the causative agent of the sexually transmitted disease syphilis, is an uncultivatable human pathogen. The geographical differences in T. pallidum genomes leading to differences in pathogenicity are not yet understood. Presently, twelve T. pallidum genomes are available to the public, all of which are American in origin and often co-infect patients with human immunodeficiency virus (HIV). In this study, we examined the T. pallidum subsp. pallidum strain Amoy, a syphilis pathogen found in Xiamen, China. We sequenced its genome using Illumina next-generation sequencing technology and obtained a nearly (98.83%) complete genome of approximately 1.12 Mbps. The new genome shows good synteny with its five T. pallidum sibling strains (Nichols, SS14, Mexico A, DAL-1, and Chicago), among which SS14 is the strain closest to the Amoy strain. Compared with strain SS14, the Amoy strain possesses four uncharacterized strain-specific genes and is likely missing six genes, including a gene encoding the TPR domain protein, which may partially account for the comparatively low virulence and toxicity of the Amoy strain in animal infection. Notably, we did not detect the 23S rRNA A2058G/A2059G mutation in the Amoy strain, which likely explains the sensitivity of Amoy strain to macrolides. The results of this study will lead to a better understanding of the pathogenesis of syphilis and the geographical distribution of T. pallidum genotypes.

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%.

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.

Prevalence of Integrase Strand Transfer Inhibitors (INSTI) Resistance Mutations in Taiwan

Antiretroviral therapy containing an integrase strand transfer inhibitor (INSTI) plus two NRTIs has become the recommended treatment for antiretroviral-naive HIV-1-infected patients in the updated guidelines. We aimed to determine the prevalence of INSTI-related mutations in Taiwan. Genotypic resistance assays were performed on plasma from ARV-naïve patients (N = 948), ARV-experienced but INSTI-naive patients (N = 359), and raltegravir-experienced patients (N = 63) from 2006 to 2015. Major INSTI mutations were defined according to the IAS-USA list and other substitutions with a Stanford HIVdb score ≧ 10 to at least one INSTI were defined as minor mutations. Of 1307 HIV-1 samples from patients never exposed to INSTIs, the overall prevalence of major resistance mutations to INSTIs was 0.9% (n = 12), with an increase to 1.2% in 2013. Of these 12 sequences, 11 harboured Q148H/K/R, one Y143R, and none N155H. Of 30 sequences (47.6%) with INSTI-resistant mutations from raltegravir-experienced patients, 17 harboured Q148H/K/R, 8 N155H, and 6 Y143C/R. Other than these major mutations, the prevalence of minor mutations were 5.3% and 38.1%, respectively, in ARV-naive and raltegravir-experienced patients. The overall prevalence of INSTI mutations remains low in Taiwan. Surveillance of INSTI resistance is warranted due to circulation of polymorphisms contributing to INSTI resistance and expected increasing use of INSTIs.

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.

Comparison of serological responses to single-dose azithromycin (2 g) versus benzathine penicillin G in the treatment of early syphilis in HIV-infected patients in an area of low prevalence of macrolide-resistant Treponema pallidum infection

OBJECTIVES

Effectiveness of single-dose azithromycin (2 g) in the treatment of early syphilis among HIV-infected patients has rarely been evaluated in the era of combination ART.

METHODS

Consecutive HIV-infected patients with early syphilis, who received 2 g single-dose azithromycin or 2.4 MU benzathine penicillin G, between 2007 and 2014, were prospectively observed. Genotypic resistance to macrolides was determined in Treponema pallidum isolates identified from clinical specimens using PCR assays. Rapid plasma reagin (RPR) titres were determined at baseline and every 3 months after treatment. Primary outcome was a decline of RPR titre by ≥4-fold at 12 months after treatment.

RESULTS

During the study period, 162 HIV-infected patients with early syphilis received benzathine penicillin G and 237 patients received azithromycin. At 12 months follow-up, the serological response rate for penicillin and azithromycin groups was 61.1% and 56.5% (P = 0.41), respectively; respective response rate was 61.1% and 65.9% (P = 0.49) if we only included patients infected with T. pallidum not harbouring macrolide resistance in the azithromycin group. In multivariate analysis, RPR titres ≥1:32 (OR 2.56; 95% CI 1.55-4.21) and prior syphilis (OR 0.54; 95% CI 0.35-0.81) were predictors of serological response. Most common adverse effects of azithromycin included diarrhoea (52.7%), nausea (22.4%), abdominal pain (18.6%), bloating (17.7%) and lassitude/somnolence (27.4%).

CONCLUSIONS

In the setting of a low prevalence of macrolide-resistant T. pallidum, 2 g single-dose azithromycin achieved a similar serological response to benzathine penicillin G in HIV-infected patients with early syphilis. Major adverse effects of azithromycin were gastrointestinal symptoms and lassitude/somnolence.

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.

Unexpectedly high prevalence of Treponema pallidum infection in the oral cavity of human immunodeficiency virus-infected patients with early syphilis who had engaged in unprotected sex practices

Between 2010 and 2014, we obtained swab specimens to detect Treponema pallidum, with PCR assays, from the oral cavities of 240 patients with 267 episodes of syphilis who reported engaging in unprotected sex practices. The detected treponemal DNA was subjected to genotyping. All of the syphilis cases occurred in men who have sex with men (MSM), and 242 (90.6%) occurred in human immunodeficiency virus-infected patients. The stages of syphilis included 38 cases (14.2%) of primary syphilis of the genital region, 76 (28.5%) of secondary syphilis, 21 (7.9%) of primary and secondary syphilis, 125 (46.8%) of early latent syphilis, and seven (2.6%) others. Concurrent oral ulcers were identified in 22 cases (8.2%). Treponemal DNA was identified from the swabs of 113 patients (42.2%), including 15 (68.2%) with oral ulcers. The most common genotype of T. pallidum was 14f/f. The presence of oral ulcers was associated with identification of T. pallidum in the swab specimens (15/22 (68.2%) vs. 98/245 (40.0%)) (p = 0.01). In multivariate analysis, secondary syphilis (adjusted OR 6.79; 95% CI 1.97-23.28) and rapid plasma reagin (RPR) titres of ≥1: 32 (adjusted OR 2.23; 95% CI 1.02-4.89) were independently associated with the presence of treponemal DNA in patients without oral ulcers. We conclude that detection of treponemal DNA in the oral cavity with PCR assays is not uncommon in MSM, most of whom reported having unprotected oral sex. Although the presence of oral ulcers is significantly associated with detection of treponemal DNA, treponemal DNA is more likely to be identified in patients without oral ulcers who present with secondary syphilis and RPR titres of ≥1: 32.

The molecular epidemiology of Treponema pallidum subspecies pallidum

Pathogens adapt and evolve in response to pressures exerted by host environments, leading to generation of genetically diverse variants. Treponema pallidum subspecies pallidum displays a substantial amount of interstrain diversity. These variants have been identified in various parts of the world, indicating transmission linkage between geographical regions. Genotyping is based on molecular characterisation of various loci in the syphilis treponeme genome, but still require further development and continued research, as new bacterial types are continually being detected. The goal for studying the molecular epidemiology of Treponema pallidum variants is the global monitoring of the transmission of genetically distinct organisms with different drug sensitivities and, potentially, different virulence proprieties.

High-dose oral amoxicillin plus probenecid is highly effective for syphilis in patients with HIV infection

BACKGROUND

Intramuscular benzathine penicillin G (BPG) is widely used for the treatment of syphilis. However, BPG is not available in some countries. This study examined the effectiveness and safety of high-dose oral amoxicillin plus probenecid for the treatment of syphilis in patients with human immunodeficiency virus type 1 (HIV-1).

METHODS

This retrospective observational study included 286 HIV-infected male patients with syphilis (median age, 36 years; median CD4 count, 389 cells/µL) who were treated with oral amoxicillin 3 g plus probenecid. Syphilis was diagnosed by both serum rapid plasma reagin (RPR) titers ≥8 and positive Treponema pallidum hemagglutination test. Patients with neurosyphilis diagnosed by cerebrospinal fluid examination were excluded. Successful treatment was defined as a at least 4-fold decrement in RPR titer.

RESULTS

The overall treatment efficacy was 95.5% (95% confidence interval [CI], 92.4%-97.7%; 273/286 patients), and efficacy for primary, secondary, early latent, late latent, and unknown duration syphilis was 93.8% (95% CI, 68.1%-99.8%; 15/16), 97.3% (95% CI, 92.9%-99.2%; 142/146), 100% (95% CI, 90.5%-100%; 37/37), 85.7% (95% CI, 58.6%-96.4%; 18/21), and 92.4% (95% CI, 81.9%-97.3%; 61/66), respectively. Treatment duration was mostly 14-16 days (49.7%) or 28-30 days (34.3%), with efficacy of 94.4% (134/142) and 95.9% (94/98), respectively; 96.3% of successfully treated patients achieved a ≥4-fold decrement in RPR titer within 12 months. Adverse events were noted in 28 (9.8%) patients, and 25 of these (89.3%) were successfully treated. Only 6% of patients underwent lumbar puncture.

CONCLUSIONS

The combination of oral amoxicillin 3 g plus probenecid was highly effective and tolerable for the treatment of syphilis in patients with HIV-1 infection.

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.

Comparison of serological response to doxycycline versus benzathine penicillin G in the treatment of early syphilis in HIV-infected patients: a multi-center observational study

BACKGROUND

While doxycycline is recommended as an alternative treatment of syphilis in patients with penicillin allergy or intolerance, clinical studies to compare serological response to doxycycline versus benzathine penicillin in treatment of early syphilis among HIV-infected patients remain sparse.

METHODS

We retrospectively reviewed the medical records of HIV-infected patients with early syphilis who received doxycycline 100 mg twice daily for 14 days (doxycycline group) and those who received 1 dose of benzathine penicillin (2.4 million units) (penicillin group) between 2007 and 2013. Serological responses defined as a decline of rapid plasma reagin titer by 4-fold or greater at 6 and 12 months of treatment were compared between the two groups.

RESULTS

During the study period, 123 and 271 patients in the doxycycline and penicillin group, respectively, completed 6 months or longer follow-up. Ninety-one and 271 patients in the doxycycline and penicillin group, respectively, completed 12 months or longer follow-up. Clinical characteristics were similar between the two groups, except that, compared with penicillin group, doxycycline group had a lower proportion of patients with secondary syphilis (65.4% versus 41.5%, P<0.0001) and a higher proportion of patients with early latent syphilis (25.3% versus 49.6%, P<0.0001). No statistically significant differences were found in the serological response rates to doxycycline versus benzathine penicillin at 6 months (63.4% versus 72.3%, P = 0.075) and 12 months of treatment (65.9% versus 68.3%, P = 0.681). In multivariate analysis, secondary syphilis, but not treatment regimen, was consistently associated with serological response at 6 and 12 months of follow-up.

CONCLUSIONS

The serological response rates to a 14-day course of doxycycline and a single dose of benzathine penicillin were similar in HIV-infected patients with early syphilis at 6 and 12 months of follow-up. Patients with secondary syphilis were more likely to achieve serological response than those with other stages.

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.