A 27-year-old woman presents with vaginal itching and unusual discharge for the past two weeks. She describes the discharge as frothy, yellow-green, and foul-smelling. She reports dyspareunia (pain during intercourse) and mild dysuria. She has had multiple sexual partners over the past six months without consistent condom use. On speculum examination, there is frothy, yellow-green discharge in the vaginal canal, erythema of the vaginal walls, and a strawberry cervix (punctate hemorrhages). A wet mount shows motile, flagellated organisms, confirming the diagnosis of trichomoniasis. What is the recommended first-line treatment for trichomoniasis in adults?
