A 30-year-old female presents with persistent vaginal discharge and vulvar pruritus, and the discharge is foul smelling. What is the most likely diagnosis?

In this scenario, the symptoms of persistent vaginal discharge, vulvar pruritus, and especially the characteristic foul-smelling discharge suggest an infection associated with Trichomonas vaginalis. Trichomoniasis is a sexually transmitted infection known to cause these symptoms, including a greenish-yellow, frothy, and foul-smelling discharge. Additionally, this infection is often accompanied by vulvar irritation, which aligns with the patient's complaint of pruritus.

While bacterial vaginosis can also present with a foul-smelling discharge due to an overgrowth of normal vaginal flora, it typically lacks significant itching or irritation. Vulvovaginal candidiasis usually presents with a thick, white discharge that is more curd-like and does not have a foul odor. Atrophic vaginitis generally affects postmenopausal women and results from estrogen deficiency, leading to vaginal dryness and often a more insipid discharge rather than a foul smell. The distinctive symptoms and characteristics of the discharge in this case align most closely with trichomoniasis.