<prompt> Chancroid is caused by?H. DucreiN. GonnorreaT. PallidumH. Influenza  <response>: Ans:A.H. Ducrei CHANCROID SOFT SORE This venereal infection is caused by the Gram-negative bacillus Haemophilus ducreyi. One to 5 days post-infection, a soft sloughy ulcer appears on the penis or vulva. The treatment of choice is erythromycin 500 mg 6-hourly for 14 days. 