Sex-Based and Age-Specific Trends in Gardnerella vaginalis Infection: An Epidemiological Study in Republic of Korea, 2018-2022

Sexually Transmitted Infections (STIs) are an important global public health issue caused by various pathogens. STI symptoms can manifest at different times, depending on the sex, age, and infection route. Here, we aimed to assess the occurrence of STIs in the Republic of Korea, explore associated global trends, and identify pathogens with high positivity rates to inform future health policies. A total of 177,599 samples were collected by U2Bio (Jangwon Medical Foundation, Seoul, Republic of Korea), a testing agency that conducts STI tests for general practitioners and semi-hospitals. Among these, 49,395 specimens were positive for Gardnerella vaginalis (GV) and were analyzed retrospectively based on sex, age, co-infection, and sample collection method. Among the pathogens isolated in the positive group, GV showed the highest prevalence at 27.8% (n = 49,395/177,599). Males were more frequently infected than females, with a higher positivity rate in younger males (20-29 years; 42.6%) than in age-matched younger females (14.3%). The highest prevalence was detected in younger males (42.6%) and older females (> 90 years; 21.4%) among the different male and female groups. GV showed co-infection with up to nine other STIs, with the highest co-infection rate with Ureaplasma spp. In summary, GV infections vary by sex, age, and specimen type, with higher rates in males despite its association with bacterial vaginosis in females. These findings suggest the need for targeted diagnostic strategies, improved STI screening programs, and tailored public health interventions to mitigate infection risks based on sex and age demographics.