What is the pathophysiology of chancroid?

Updated: Aug 05, 2019
  • Author: Joseph Adrian L Buensalido, MD; Chief Editor: Pranatharthi Haran Chandrasekar, MBBS, MD  more...
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Answer

Chancroid is caused by H ducreyi, a small, gram-negative, facultative anaerobic bacillus that is highly infective. It is pathogenic only in humans, with no intermediary environmental or animal host. H ducreyi enters the skin through disrupted mucosa and causes a local inflammatory reaction. It produces a cytocidal distending toxin that appears to be responsible for its destructive effects.

H ducreyi penetrates the skin through breaks in the mucosal barriers and microabrasions on the skin. It produces a cytocidal distending toxin (HdCDT), which causes cell cycle arrest and apoptosis/necrosis of human cells and contributes to the aggravation of ulcers. [13] Phagocytosis by macrophages is also impaired. [14, 15] Other virulence mechanisms include LspA proteins, which have antiphagocytic functions, DsrA map, which facilitates adherence, and an influx transporter that protects H ducreyi from antimicrobial killing. [16, 17, 18]

H ducreyi is transmitted sexually by direct contact with purulent lesions and by autoinoculation to nonsexual sites, such as the eye and skin. The organism has an incubation period of 1 day to 2 weeks, with a median time of 5-7 days. The disease typically begins as a small inflammatory papule at the site of inoculation; within days, the papule may erode to form an extremely painful deep ulceration. Without treatment, the lesions may last weeks to months, and complications such as suppurative lymphadenopathy are more likely. [4, 19, 20]


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