23 years old male had unprotected sexual intercourse with a commercial sex worker. Two weeks later, he developed a painless, indurated ulcer on the glans that exuded clear serum on pressure. Inguinal lymph nodes in both groins were enlarged and not tender. The most appropriate diagnostic test is:
Ans. is 'b' i.e., Dark field microscopy of ulcer discharge (Ref: Harrison, 17th/e, p. 1384 ,18th/e, p. 1043 and19th/e, p. 1132; Ananthanarayan, 9th/e, p. 370)History is indicating towards syphilis and T. pallidum can be seen from ulcer discharge by using Dark field microscopy.
Gram's stain of ulcer discharge
Dark field microscopy of ulcer discharge
Giemsa stain of lymph node aspirate
ELISA for HIV infection
Bacteria