- Pathogens that cause sexually transmitted infections (12): Chlamydia trachomatis, Neisseria gonorrhoeae, Mycoplasma genitalium, Mycoplasma hominis, Ureaplasma urealyticum, Trichomonas vaginalis, Ureaplasma parvum, Candida albicans, Treponema pallidum, Herpes simplex virus 1, Herpes simplex virus 2 and Gardnerella vaginalis