Incidence of sexually transmitted infections and screening models among pre-exposure prophylaxis users.

INTRODUCTION: There is discussion about the frequency of STI screening among pre-exposure prophylaxis (PrEP) users. The aim of this study was to analyse the incidence of STIs and to evaluate different screening models in order to optimise the follow-up. METHODOLOGY: A prospective study was conducted between 2017 and 2023, including 138 PrEP users in a STI clinic. Participants were tested for STIs every three months. Unscheduled visits were performed for those with STI-related symptoms or for people who were notified for an STI by a sexual partner. We performed a survival analysis of repeated events, estimating the cumulative incidence (CI) and incidence rate (IR). RESULTS: The overall CI by quarterly screening was 8.3 (95% CI: 7.6-9.1) infections per person over six years, with a decreasing trend. The most frequently diagnosed pathogen was Neisseria gonorrhoeae, with a IR of 0.76 (95% CI: 0.68-0.84). If the frequency of screening is reduced to every six months, the IR of STIs is reduced by (95% CI: 0.5-0.66) infections per user per year, and at 12 months by 0.82 (95% CI: 0.73-0.89). In the case of no pharyngeal or urethral screening, IR is reduced by 0.37 (95% CI: 0.32-0.42) infections per person per year and in those over 35 years of age by 0.33 (95% CI: 0.25-0.4). Eliminating unscheduled visits, the reduction in IR is 0.33 (95% CI: 0.24-0.42). CONCLUSIONS: The incidence of STIs among PrEP users is high, especially in the rectum, but it does not increase over time. STI screening could be optimised reducing the frequency of pharyngeal and urethral testing, particularly in those over 35 years of age. It is essential to redistribute health resources for unscheduled visits, which have been shown to be the most cost-effective screening.

Is dark-field microscopy still useful for the primary syphilis diagnosis in the 21ST century?

INTRODUCTION: Serological test for primary syphilis could be negative the first 5-15 days. The aim of this study was to evaluate the benefit of including dark field microscopy (DFM) in the diagnosis algorythm for primary syphilis. MATERIALS/METHODS: Patients attended to a sexual transmission diseases clinic of Madrid, from 2015 to 2019, for a genital ulcer with clinical suspicion of primary syphilis. They were tested for DMF and serological test (EIA/TPPA/RPR). RESULTS: Over the total amount of samples (806), 53.2% (429) were positive for DFM. Thus, the 48% of the 429 patients had negative serological test (EIA/RPR) of which the 77.6% were positive at TPPA. CONCLUSIONS: DFM allows primary syphilis early diagnosis, even without serological test. If no direct detection methods are available, for patients without history of syphilis, TPPA could help to diagnose primary syphilis.

Low use of condom and high STI incidence among men who have sex with men in PrEP programs.

OBJECTIVE: Since the recent introduction of preexposure prophylaxis (PrEP), several studies have reported a decrease in the use of condoms and a rise in STIs among users. This rise in risk behavior associated with the advent of PrEP is known as "risk compensation." The aim of this study is to measure clinical and behavioral changes associated with the introduction of PrEP by analyzing condom use for anal intercourse, number of sexual partners, sexualized drug use and STI incidence. METHODS: We performed a retrospective descriptive study of PrEP users followed every 3months over a 2-year period spanning 2017-2019 in a referral clinic specializing in STI/HIV in Madrid, Spain. One hundred ten men who have sex with men and transgender women underwent regular screening for STIs and hepatitis C virus (HCV) infection. Sociodemographic, clinical, and behavioral data were gathered for all subjects studied. RESULTS: The risk compensation observed in this study consisted primarily of a lower rate of condom use, while the number of sexual partners and recreational drug consumption remained stable. We observed a very high incidence of STIs in this sample, particularly rectal gonorrhea and chlamydia. The factors shown to be independently associated with the presence of an STI on multivariate analysis were age below 30 years and over 10 sexual partners/month. CONCLUSION: The incidence of STI acquisition was higher than expected, indicating a need for strategies to minimize this impact, particularly among younger individuals with a higher number of sexual partners.

Is dark-field microscopy still useful for the primary syphilis diagnosis in the 21ST century? / ¿Sigue siendo útil la microscopia de campo oscuro en el diagnóstico de la sífilis primaria en el siglo XXI?

INTRODUCTION: Serological test for primary syphilis could be negative the first 5-15 days. The aim of this study was to evaluate the benefit of including dark field microscopy (DFM) in the diagnosis algorythm for primary syphilis. MATERIALS/METHODS: Patients attended to a sexual transmission diseases clinic of Madrid, from 2015 to 2019, for a genital ulcer with clinical suspicion of primary syphilis. They were tested for DMF and serological test (EIA/TPPA/RPR). RESULTS: Over the total amount of samples (806), 53.2% (429) were positive for DFM. Thus, the 48% of the 429 patients had negative serological test (EIA/RPR) of which the 77.6% were positive at TPPA. CONCLUSIONS: DFM allows primary syphilis early diagnosis, even without serological test. If no direct detection methods are available, for patients without history of syphilis, TPPA could help to diagnose primary syphilis.