{
  "abstract": "Background Sexually transmitted infections (STIs) incidence is high among PrEP cohorts, driven by high-risk sexual behaviours and systematic asymptomatic screening. Emerging evidence questioning the benefit of quarterly Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) screening in asymptomatic men who have sex with men (MSM) on PrEP is currently challenging international guidelines. This study assessed overall STI occurrence in our cohort and, focusing on 2025 data, evaluated CT/NG incidence, risk factors, and determinants of symptomatic presentation.Methods Retrospective study including all individuals initiating PrEP between June 2018 and December 2025 at the Bergamo PrEP clinic (Italy). Incident STIs included gonorrhoea, chlamydia, syphilis, Mycoplasma genitalium, warts, Mpox, genital herpes and viral hepatitis. Follow-up (FU) visits were scheduled every three and four months for daily and on-demand users, respectively. Multiple logistic regression models examined predictors of CT/NG incidence and symptomatic presentation in 2025, including age, PrEP regimen, prior CT/NG infection and median number of quarterly sexual partners. Symptoms were defined as urethritis, pharyngodynia or proctitis.Results Of 611 individuals commencing PrEP, 150 were enrolled in 2025; 98% were cisgender males (96% GBMSM), median age was 36 years (IQR 30–44). On-demand PrEP was chosen by 383 (63%) at baseline. Median FU was 17 months (IQR 6–28); 150 users withdrew from FU. Among 481 users with at least one FU visit, 277 (58%) had at least one STI (total STIs: 827); 80 users (17%) had ≥4 incident STIs, accounting for 505 (61%) of all diagnoses (high-rate reinfection group). In 2025, 394 users attended at least one FU visit (1,078 total FU visits; median 3, IQR 2–4). NG was diagnosed in 109 users (153 infections) and CT in 63 users (74 infections). 43 (39%) NG-positive and 30 (48%) CT-positive users belonged to the high-rate reinfection group. Most infections were asymptomatic; symptoms were reported in only 27 (25%) and 9 (14%) users with NG and CT, respectively. Among 22 culture-positive NG infections, 68% were in symptomatic patients. On multiple logistic regression model, having >5 quarterly sexual partners and prior CT/NG infection were associated with higher risk of incident CT/NG ( table 1). A separate model for symptomatic gonorrhoea (chlamydia was excluded due to the low number of symptomatic cases) showed that absence of prior CT/NG infection was associated with higher risk of symptomatic presentation (p value=0.054).Conclusions CT/NG risk was higher in users with prior CT/NG infections and higher number of sexual partners. Over 50% of 2025 CT/NG infections occurred outside the high-reinfection group, suggesting a remodelling of risk distribution. Prior CT/NG infections appeared protective against symptomatic gonorrhoea. Further studies are needed to characterise determinants of symptomatic infection and support tailored screening strategies.Abstract SC6 Table 1Determinants of any incident gonorrhoea and chlamydia",
  "authors": [
    {
      "affiliations": [
        "Infectious Diseases Unit, ASST Papa Giovanni XXIII, Bergamo, Italy"
      ],
      "name": "S Venturelli"
    },
    {
      "affiliations": [
        "School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy"
      ],
      "name": "G Ghilardi"
    },
    {
      "affiliations": [
        "School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy"
      ],
      "name": "E Nespoli"
    },
    {
      "affiliations": [
        "Infectious Diseases Unit, ASST Papa Giovanni XXIII, Bergamo, Italy"
      ],
      "name": "L Comi"
    },
    {
      "affiliations": [
        "Infectious Diseases Unit, ASST Papa Giovanni XXIII, Bergamo, Italy"
      ],
      "name": "F Borghi"
    },
    {
      "affiliations": [
        "FROM Research Foundation: Fondazione per la Ricerca Ospedale di Bergamo – ETS, Bergamo, Italy"
      ],
      "name": "A Francavilla"
    },
    {
      "affiliations": [
        "Infectious Diseases Unit, ASST Papa Giovanni XXIII, Bergamo, Italy"
      ],
      "name": "D Ripamonti"
    },
    {
      "affiliations": [
        "Infectious Diseases Unit, ASST Papa Giovanni XXIII, Bergamo, Italy"
      ],
      "name": "F Crippa"
    }
  ],
  "title": "SC6 Determinants of asymptomatic and symptomatic incident chlamydia and gonorrhoea infections among PrEP users",
  "uid": "aa960dc4-7f3a-56d5-a2da-89b424fc9d4a"
}