Background Serologic tests for syphilis (STS) results at time of diagnosis are the basis for evaluating response to syphilis therapy. Following treatment, however, STS titers may continue to increase for several weeks. We evaluated RPR titer variation over the 14 days following therapy using data from a recent large, prospective RCT. Methods Prospectively enrolled participants in North America and Madagascar with primary, secondary or early latent syphilis were randomly assigned to penicillin, doxycycline (in the case of penicillin allergy) or azithromycin treatment. Blood for RPR analysis was drawn at days 0, 7, and 14 post-treatment. All RPR titers were determined simultaneously at a central laboratory. Results 470 patients had data available for at least 2 of 3 RPR measurements. Overall, 20% of patients showed a titer increase of at least one dilution in the 14 days following therapy. The greatest proportion of titer increases following therapy was seen in patients with primary syphilis. Comparing outcome of therapy using the initial (day 0) RPR titer vs. the maximal RPR titer (over 14 days), resulted in outcome reclassification in 2.98% of participants. Conclusions Despite the fact that about 20% of early syphilis patients had increases in RPR titers immediately following treatment, these changes rarely influenced assessment of therapeutic outcome. Only 3% of patients treated would have been reclassified.

Early syphilis therapy was a focus of intense research in the early 20th century with many and varied approaches being used. The development of penicillin and its efficacy in the treatment of syphilis transformed syphilis management for many with and at risk for infection. However, problems such as beta-lactam allergies and the desire for easily administered, alternate therapies have led to evaluation of multiple other drugs, with doxycycline currently recommended as the main alternative. Ceftriaxone and azithromycin have been shown to be effective, however, each has its own difficulties. Follow-up relies on serological testing, leading to concerns when these tests do not decline appropriately. Given concerns about the potential for increased risk for treatment failure, patients with HIV and pregnant women are of particular concern.

Minimal sexual health assessment is being performed during the time surrounding initial prescription of erectile dysfunction medication. Further work needs to evaluate patient and provider barriers to basic elements of sexual health care, such as taking sexual histories or screening for sexually transmitted infections.

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women were invited to continue follow-up in an open cohort study. These post-trial data were analysed to test the hypothesis that the treatment effect would persist in the absence of PPT. Methods Data were obtained from women who completed all 12 RCT visits and attended $1 cohort study visit within 120 days of their final RCT visit. We used Andersen-Gill proportional hazards models to estimate the post-trial effect of the intervention vs placebo on the incidence of BV by Gram stain (Nugent score $7) and Lactobacillus species by culture on Rogosa agar. Results The RCT enrolled 310 subjects (155 per arm), of whom 165 (83 active and 82 placebo) were included in this analysis. Included subjects were slightly older (median (IQR): 33 years (29e39) vs 30 years (26e35); p<0.001) and reported a longer duration of sex work (median (IQR): 6 years (2e11) vs 3 years (1e6); p<0.001) compared to those excluded. At the final RCT visit, which represented the baseline visit for this analysis, demographic and behavioural characteristics were similar by arm. The prevalence of BV at the final RCT visit was 16% in the active arm and 43% in the placebo arm (p<0.001). The post-trial incidence of BV was 260/100 person-years (p-yrs) in the active arm vs 358/100 p-yrs in the placebo arm (HR¼0.76; 95% CI: 0.51% to 1.12%). The prevalence of Lactobacillus colonisation at the final RCT visit was 17% in the active arm and 18% in the placebo arm (p¼0.81). The post-trial incidence of Lactobacillus colonisation was 180/100 p-yrs in the active arm vs 127/100 p-yrs in the placebo arm (HR¼1.42; 95% CI: 0.85% to 2.71%). Conclusions Despite a decrease in BV and an increase in Lactobacillus colonisation during the RCT, the effect of PPT was not sustained during the 120 days following cessation of the intervention. New interventions that reduce BV recurrence and promote long-term Lactobacillus colonisation without the need for ongoing PPT or suppressive therapy are needed. O3-S5.05 RPR TITRE VARIATION FOLLOWING EARLY SYPHILISTHERAPY: A POTENTIAL CONFOUNDER OF TREATMENT OUTCOME ASSESSMENT Objective Serologic tests for syphilis (STS) results at the time of diagnosis are the basis for evaluating response to syphilis therapy. Following treatment, however, STS titres may continue to increase for several weeks. In a recent study comparing azithromycin to penicillin or doxycycline for early syphilis treatment, patients had RPR titres measured initially, at 7 and at 14 days following treatment. We evaluated variation in RPR titres over the 14 days following therapy, hypothesising that RPR titre changes would vary with stage and initial titre. Methods Prospectively identified HIV-seronegative participants at five North American and three Madagascar sites with primary, secondary or early latent syphilis were randomly assigned to penicillin, doxycycline (in the case of penicillin allergy) or azithromycin treatment. Blood for RPR analysis was drawn at days 0, 7, and 14 post-treatment. All RPR titres were determined simultaneously at a central laboratory. Analysis w...