Which Laboratory Test Is Most Appropriate for Confirming the Diagnosis of Urethritis in Mr. Santos

Mr. Santos, a 45-year-old Male, Presents to the Clinic with Complaints of Dysuria, Frequency and Urgency. He Denies Any History of Recent Sexual Activity. Upon Physical Examination, the Nurse Notices Erythema and Edema of the Urethral Meatus. the Nurse Suspects Urethritis and Orders Laboratory Tests to Confirm the Diagnosis