Specific detection of Treponema pallidum in clinical samples: validation of a qPCR assay combining two genomic targets.

OBJECTIVES: We evaluated a real-time quantitative PCR (qPCR) for detection of the Treponema pallidum (TP) genome in clinical samples through simultaneous detection of two genomic targets. METHODS: We performed qPCR with TaqMan technology using two TP genes, polA and tpp47, as targets, with an internal positive control. The qPCR assay was compared with syphilis diagnosis based on a combination of clinical examination, serological results and inhouse nested PCR (nPCR). Samples were analysed at the National Reference Center for STIs at Cochin Hospital in Paris. RESULTS: In total, from October 2010 to December 2016, 320 documented clinical samples (mucosal and cutaneous swabs) were collected from patients with or without syphilis attending STI centres in France. The qPCR had an overall sensitivity of 89% (95% CI 85.1% to 92.1%), a specificity of 100%, a positive predictive value of 100% and a negative predictive value of 88% (95% CI 84.3% to 91.5%). The agreement between qPCR and nPCR results was 94% (κ=0.88, 95% CI 0.83 to 0.93). Calibration of the qPCR assay, by cloning both the polA and tpp47 genes, defined the detection threshold as 1 copy/µL of DNA elution. CONCLUSIONS: We validated a new qPCR for detecting the TP genome in clinical samples with excellent sensitivity and specificity. The cloning of polA and tpp47 genes for calibration would be interesting in the evaluation of bacterial loads in samples.

Doxycycline versus azithromycin for the treatment of anorectal Chlamydia trachomatis infection in women concurrent with vaginal infection (CHLAZIDOXY study): a multicentre, open-label, randomised, controlled, superiority trial.

BACKGROUND: Anorectal infections with Chlamydia trachomatis are commonly found in women. Although the efficacy of doxycycline and azithromycin is comparable in the treatment of urogenital infection, their efficacies toward anorectal infection remain unclear. We therefore aimed to compare a single dose of azithromycin with a 7-day course of doxycycline for the treatment of anorectal C trachomatis infection in women with concurrent vaginal infection. METHODS: We did a multicentre, open-label, randomised, controlled, superiority trial involving four sexually transmitted infection screening centres and three pregnancy termination centres in France. We included sexually active adult women (≥18 years) with a positive C trachomatis vaginal swab who agreed to provide self-collected anorectal swabs for C trachomatis detection. Participants were randomly assigned (1:1), using block sizes of six and eight and stratification by each investigating centre, to orally receive either azithromycin (a single 1-g dose, with or without food) or doxycycline (100 mg in the morning and evening at mealtimes for 7 days [ie, 100 mg of doxycycline twice per day for 7 days]). All laboratory staff who did the bacteriological analyses, but not the participants and the investigators, were masked to the treatment groups. The primary outcome was the microbiological anorectal cure rate defined as a C trachomatis-negative nucleic acid amplification test (NAAT) result in anorectal specimens 6 weeks after treatment initiation among women who had a baseline C trachomatis-positive anorectal NAAT result. The primary analysis was done in the modified intention-to-treat population, with multiple imputation, which included all women who underwent randomisation and had a C trachomatis-positive vaginal and anorectal NAAT result at baseline. Adverse events were reported in all women who underwent randomisation. This study is registered with ClinicalTrials.gov, number NCT03532464. FINDINGS: Between Oct 19, 2018, and April 17, 2020, we randomly assigned a total of 460 participants to either the doxycycline group (n=230) or the azithromycin group (n=230). Four (1%) of 460 participants were excluded because they refused to take doxycycline or were found to be ineligible after randomisation. Among the 456 participants, 357 (78%) had a concurrent C trachomatis-positive anorectal NAAT result at baseline; 184 (52%) of 357 were in the doxycycline group and 173 (48%) were in the azithromycin group (ie, the modified intention-to-treat population). Microbiological anorectal cure occurred in 147 (94%) of 156 participants in the doxycycline group (28 missing values) versus 120 (85%) of 142 in the azithromycin group (31 missing values; adjusted odds ratio with imputation of missing values 0·43 [95% CI 0·21-0·91]; p=0·0274). Reported adverse events possibly related to treatment were notified in 53 (12%) of 456 women: 24 (11%) of 228 in the doxycycline group and 29 (13%) of 228 in the azithromycin group. Gastrointestinal disorders were the most frequently occurring, in 43 (9%) of 456 women: 17 (8%) of 228 in the doxycycline group and 26 (11%) of 228 in the azithromycin group. INTERPRETATION: The microbiological anorectal cure rate was significantly lower among women who received a single dose of azithromycin than among those who received a 1-week course of doxycycline. This finding suggests that doxycycline should be the first-line therapy for C trachomatis infection in women. FUNDING: French Ministry of Health. TRANSLATION: For the French translation of the abstract see Supplementary Materials section.

Trends and determinants of condomless sex in gonorrhoea patients diagnosed in France through the sentinel surveillance network ResIST, 2005-2014.

BACKGROUND: Gonorrhoea is increasing in France since its resurgence in the late 1990's. Understanding trends of condomless sex is a requirement to tailor prevention toward most exposed individuals. This study aims to analyse trends and determinants of condomless penetrative sex (PS) in MSM and heterosexuals diagnosed with gonorrhoea in France. METHODS: A standardized self-administered questionnaire filled by 3453 patients was used to monitor condomless sex through the sentinel surveillance network ResIST between 2005 and 2014. Trends were used to describe consistent condom use for penetrative sex (PS). A logistic regression model analysed patients' characteristics associated with condomless PS. RESULTS: Between 2005 and 2014, condomless PS increased regardless of sexual orientation. Condomless PS was particularly common among HIV positive men who have sex with men (MSM (65%)). People living in metropolitan regions outside Paris area (adjusted odds-ratio (AOR) [95% CI] =1.33[1.12-1.58]) were more likely to engage in condomless PS. Conversely, MSM (AOR [95% CI] =0.21 [0.16-0.29]), HIV seronegative patients (AOR [95% CI] =0.68 [0.51-0.89]), patients diagnosed in hospital (AOR [95% CI] = 0.66 [0.45-0.97]) and multi-partners (≥ 10 partners, AOR [95% CI] = 0.54 [0.40-0.74]) were more likely to use condoms. CONCLUSIONS: These findings highlight a decreasing use of condom in MSM and heterosexuals diagnosed with gonorrhoea. Prevention strategies should take in account drivers of condomless sex in a context of uncontrolled STI epidemics.

Surveillance of Antibiotic Resistance Genes in Treponema Pallidum Subspecies Pallidum from Patients with Early Syphilis in France.

Benzathine penicillin G (BPG) is the reference treatment for early syphilis, but shortages have recently been reported, highlighting a need for the validation of alternative treatments. The aim of this study was to evaluate the genomic resistance of Treponema pallidum subspecies pallidum (TPA) to macrolides and doxycycline in France. Swabs from genital, anal, oral and cutaneous lesions were obtained from 146 patients with early syphilis in France. They were screened for mutations conferring resistance to macrolides and doxycycline by nested PCR and sequencing. Resistance to macrolides was detected in 85% of the isolates, but no point mutations conferring doxycycline resistance were detected. These findings confirm that, in France, resistance to macrolides is widespread. Moreover, we confirmed the absence of genomic resistance to doxycycline in the TPA strains. Therefore, doxycycline could be safely recommended as an alternative to BPG for the treatment of early syphilis.

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.