Chacroid is caused by?

See APPENDIX-47 for list of “STDs” CHANCROID (SOFT SORE) This venereal infection is caused by the Gram-negative bacillus Haemophilus ducreyi. One to 5 days postinfection, a soft sloughy ulcer appears on the penis or vulva. The treatment of choice is erythromycin (500 mg 6-hourly for 14 days).