A 25-year-old man presents with a 2-day history of painful urination and urethral discharge. He reports unprotected sexual intercourse with a new partner 10 days ago. A urethral swab is taken for NAAT testing. Gram stain of the discharge shows Gram-negative intracellular diplococci. According to BASHH guidelines, what is the most appropriate empirical treatment whilst awaiting NAAT results?