86 - Haemophilus ducreyi

Abstract

Haemophilus ducreyi is a fastidious, gram-negative, facultatively anaerobic coccobacillus that causes chancroid, which is also known as soft chancroid or ulcus molle. This is a sexually transmitted disease (STD) with characteristic mucocutaneous ulcers on the external genitals and often with a unilateral inguinal bubo. The disease is endemic in developing countries, particularly Africa, where an association between genital ulcers and transmission of human immunodeficiency virus (HIV) is established. H. ducreyi is a small nonmotilc, nonspore-forming gram-negative pleomorphic coccobacillus. It is a fastidious, slow-growing, microaerophilic organism that is difficult to isolate from clinical specimens, and it requires selective, enriched media for growth. Colonies can be pushed across the agar surface intact, indicating adherence of cells to each other within colonies. The accurate diagnosis of the aetiological agent responsible for genital ulcers is important because of the need for the specific antimicrobial treatment of different genitourinary diseases. The diagnosis of chancroid is primarily based on the clinical features and character of the lesions. The clinical diagnosis of chancroid and other genital ulcerations can be difficult because of variations in clinical picture, the mimicry of other conditions, and co-infection. The laboratory confirmation of chancroid is important, but it is difficult in that special media, conditions and expertise are required reliably to culture H. ducreyi.