A 26 year old male with recent history of unprotected sexual intercourse comes to opd with complaints of painless, indurated ulcer over the glans which exuded clear serum. Bilateral painless inguinal lymphadenopathy is also present. The most appropriate diagnostic test is:
History of sexual intercourse, painless and hard ulcer (chancre) and painless inguinal lymphadenopathy is suggestive of primary syphilis.
Dark ground examination is done to demonstrate spirochetes.
Gram stain of ulcer discharge
ELISA for HIV infection
Dark ground microscopy of ulcer discharge
Giemsa stain of lymph node aspirate