This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
Chacroid is caused by? 
Select and explain. 
A. N. Gonnorrea, B. H. Ducrei, C. T. Pallidum, D. H. Influenza
B: H. Ducrei
Answer: B: H. Ducrei 
Explanation: 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).