Problem:
A previously healthy 23-year-old female presents to the clinic for a routine exam. She has not had any problems since her last visit three years ago. She has had new sexual partners in the last 6 months and rarely uses condoms. Her last menstrual period was one week ago. Her pregnancy test is negative. On exam, she is well appearing, and her vital signs are within normal limits. The exam of her heart, lungs, and abdomen are also normal. An exam of her external genitalia reveals a single indurated, well-circumscribed painless ulcer on the left side of her vulva. In addition to screening for gonorrhea and chlamydia, which of the following test is most likely to reveal the correct diagnosis? A. A non-treponemal test B. A vulvar biopsy C. Nucleic Acid Amplification Testing (NAAT) for Herpes simplex virus (HSV) D. A bacterial culture