Infectious Disease Online
Pathology of Chancroid (Haemophilus Ducreyi Infection)
Chancroid is a sexually transmitted bacterial infection caused by Haemophilus ducreyi , a short gram-negative bacillus that appears in tissue as clusters of parallel bacilli and as chains (said to resemble schools of fish).
The bacillus is highly infectious and invade on contact, through the skin or mucous membranes.
Chancroid is common in tropical and subtropical regions.
It is a major genital ulcerative disease in Africa, Southeast Asia, the Caribbean, and Latin America.
It is more frequent in men than women and is associated with promiscuity and poor personal hygiene.
The lesions are located on the skin and mucous membranes of the genitalia.
A plaque develops 1 to 14 days after contact, becomes pustular, and ulcerates.
The ulcers rarely exceed 2.0 cm in diameter, although large and mutilating ulcers have been described.
Multiple ulcers are common, and in rare cases there are extragenital lesions of the tongue, lips, and fingers.
7 to 10 days after the appearance of primary lesion, half of the patients develop unilateral, painful, suppurative, inguinal lymphadenitis (a bubo).
The skin becomes inflamed, breaks down, and drains pus from the underlying node.
At the time the bubo develops, the patient has systemic symptoms, including headache and fever.
Microscopically, the infected epithelium over the papule becomes acutely inflamed and necrotic, and sloughs. Image
The typical ulcer has three zones, which overlap and merge.
The superficial zone contains neutrophils, fibrin, erythrocytes, and debris.
The broad middle zone comprises edematous, inflamed granulation tissue.
Finally, a deep zone contains plasma cells and lymphocytes concentrated around vessels.
The lymphnodes enlarge, become necrotic and erupt through the skin.
The diagnosis is made by identifying the bacillus in tissue sections or gram stained smears prepared from the ulcer or aspirated buboes.
H. ducreyi can be cultured on selective media, but with difficulty. DNA amplification techniques have shown improved diagnostic sensitivity but are only performed in a few laboratories.
Erythromycin is usually effective.
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