B-148 Epidemiological Analysis of Sexually Transmitted Infections in South Korea: Co-Infection Patterns and Pathogen Correlations

Background Sexually transmitted infections (STIs) refer to infections transmitted through sexual contact, including asymptomatic cases. Data on co-infections among STI pathogens based on different specimen types have been accumulating with the increasing use of multiplex PCR for STI diagnosis. This study retrospectively analyzed the epidemiological characteristics of STIs using multiplex PCR test results from South Korea(2018-2024), focusing on co-infections. Methods We analyzed multiplex PCR test results for 12 STI pathogens from January 2018 to September 2024 in individuals aged 10 to 90, conducted by Eone Laboratories. The pathogens included Neisseria gonorrhoeae (NG), Chlamydia trachomatis (CT), Mycoplasma hominis (MH), Trichomonas vaginalis (TV), Ureaplasma urealyticum (UU), Mycoplasma genitalium (MG), Herpes simplex virus type 1 (HSV1), Herpes simplex virus type 2 (HSV2), Gardnerella vaginalis (GV), Treponema pallidum (TP), Candida albicans (CA), and Ureaplasma parvum (UP). The dataset included information on gender, age, specimen type, and test date. Multiplex PCR reaction was performed using NextGene STI-12 Detection Kit (EONEBIOTECH, Republic of Korea) with an CFX 96 real-time PCR system(Bio-Rad, Republic of Korea). We analyzed the positivity rates by gender, age, and specimen type. Additionally, association rule mining was applied to evaluate co-infection patterns, and lift indices were calculated to assess the strength of associations between pathogens. Result From 2,694,547 specimens, 32,334,564 STI test results were obtained, with 3,093,258 positive cases (9.6%). Female specimens comprised 70.1%, and male 29.9%.. Among the specimens, 40.0% were negative for all pathogens, 25.8% were positive for a single pathogen, and 34.2% had co-infections with two or more pathogens. Pathogen positivity rates showed that in females, GV, UP, CA, UU, and MH had a positivity rate above 10%, while in males, UU, CT, and UP had a positivity rate exceeding 5%. NG and CT had higher positivity in males than females, peaking in individuals in their 10s and 20s, and declining with increasing age. Age-specific positivity rates revealed that, exception of TV and GV in males and HSV2 in females, all STI pathogens peaked in individuals in their 10s and 20s. In females, UU, MH, TV, GV, and UP exhibited a biphasic peak pattern, with the first peak occurring in individuals in their 10s and 20s, followed by a second peak in their 50s and 60s. A comparison of positivity rates by specimen type in female samples revealed that vaginal discharge specimens had 1.28 to 8.19 times higher positivity rates than urine specimens, indicating higher sensitivity for STI detection in female. Co-infection analysis revealed that CT-NG and TV-MH had a lift index of =3 in both males and females, indicating a strong co-occurrence. When lift indices were analyzed separately for individuals aged 10–30 and those over 30, the absolute values varied by age group; however, co-infection patterns were consistent within the same gender but differed between males and females. Conclusion This study assessed the associations among major STI pathogens based on multiplex PCR test results and analyzed their epidemiological characteristics. Further research is needed to incorporate clinical symptom data and elucidate the biological interactions of highly associated pathogens.