<prompt> Painful ulcers over genitalia are caused byPrimary syphilisGranuloma inguinaleChanchroidLymphogranuloma venerum  <response>: Ans. c Chancroid. Ref. Ananthnarayan, 6th 326, Harrison, Medicine, 15th1004Painful ulcer on the penis is due to Haemophilus ducreyi or chancroid or soft chancre.Differential diagnosis of ulcers on genitalia is.Herpes simplex Organisms causing an ulcer on genitaliaCommentsChancroid It is acute onset, painful ulcer, preceded by vesiculopustule, causes multiple ulcers, with a soft base, tender, bleeding ulcer, the floor of ulcer is formed by the slough, with undermined edges, purulent profuse discharge surr by the inflammatory skin, progresses fast. Caused by Haemophilus ducreyii. Smear shows Gram-negative bacilli in chains.Granuloma inguinale Caused by Calymmatobacterium granulomatis,Primary syphilis Condyloma lata Treponema pallidum. Hard chancreHerpes simplex 