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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.
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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.
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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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