Page 178 - The Netter Collection of Medical Illustrations - Integumentary System_ Volume 4 ( PDFDrive )

Plate 6-3 Integumentary System

Haemophilus
Soft chancre ducreyi in a
of chancroid “school of
with surrounding fish” pattern
redness with
CHANCROID surrounding
neutrophils
Chancroid is a sexually transmitted disease caused by
Haemophilus ducreyi. Infection with this bacterium is one
of the most common causes of acute genital ulcerations
in the world. Although it is most frequently encoun-
tered in Africa and Asia, it can be seen worldwide.
Infection with this agent is frequently associated with
other sexually transmitted diseases. H. ducreyi infection Chancroid under
has been shown to increase the likelihood of contract- foreskin with
ing the human immunodeficiency virus (HIV) after marked adenitis
exposure. Although specialized serology testing is being Swollen
developed, the diagnosis is based on the clinical sce- lymph nodes
nario and culture results. (buboes) can
Clinical Findings: H. ducreyi is transmitted via sexual spontaneously
contact, and the first sign of the disease is the formation drain to the
of a papule at the site of inoculation. The papule occurs, skin surface.
on average, 3 to 5 days after exposure. The papule,
which is often surrounded by a red halo, quickly turns
into a vesiculopustule and then a painful ulceration.
The ulcer is nonindurated and has undermined edges
with a well-demarcated boundary. If left untreated, the
ulcerations can become enormous and serpentine in
appearance. The base of the ulcer has a gray appearance
with granulation tissue present. The infection is associ-
ated with massive inguinal adenitis, termed buboes,
in about 50% of cases. The disease is transmitted by
unprotected sexual intercourse with an infected indi-
vidual. Women may develop subclinical undetected
disease, in which case they can act as carriers for trans-
mission. This is likely the reason that sexual intercourse
with female prostitutes increases one’s chance of devel-
oping disease. Active disease is much more frequently
encountered in males, in a 4 : 1 ratio.
Pathogenesis: H. ducreyi is a gram-negative coccoba-
cillus. The organism is transmitted from one human
host to another by intimate physical contact. The bac-
terium requires a break in the integrity of the epidermis
to gain entrance to the body. It then multiples locally
and forms the initial papule, which soon becomes a
pustule teeming with bacteria. Once the papulopustule
ulcerates, the bacterial load is high and allows for
further transmission. It has been shown that the bacte-
ria can be shed from nonulcerated lesions. The forma-
tion of ulcerations on epidermis that opposes the
original ulcer has been termed a “kissing ulcer” and is
caused by direct autoinoculation of the bacteria. The
bacteria cannot live long outside its human host, and
this characteristic can make it difficult to properly Chancroid ulcerations show a well-demarcated
culture. Many virulence factors have been detected, border and a gray discolored base.
including the cell surface lipooligosaccharide protein.
The bacteria grow on chocolate agar culture medium.
Histology: A skin biopsy from the edge of the ulcer
may be helpful in diagnosis. There are three zones
of inflammation from superficial to deep. Zone 1 is the observed in skin biopsy specimens. Culturing of reason, the disease is more difficult to treat in patients
necrotic superficial tissue. The second zone is the the bacteria is the best means to firmly make the who have a coexisting HIV infection. This may be
largest and consists of a proliferation of freshly made diagnosis. because HIV-positive patients have a lowered cell-
blood vessels. The last zone is a deep layer consisting Treatment: Treatment can be accomplished with mediated immunity, and an intact cell-mediated
of an inflammatory infiltrate with many plasma cells. azithromycin, erythromycin, or ceftriaxone. The clini- immune system is needed to treat H. ducreyi infection.
Detection of the bacteria is difficult on tissue biopsies cian should also consider treating empirically for other Surgical incision and drainage of fluctuant nodules
unless the bacterial load is tremendous. If a high burden sexually transmitted diseases, because they tend to con- should be considered as an adjunct to oral antibiotics.
of bacteria is present, they may be seen on microscopy gregate together. This is especially true of gonorrhea, Drainage decreases the bacterial load and potentially
lined up in a “school of fish” pattern. This is rarely which is often a coinfection with H. ducreyi. For some makes antibiotic therapy more effective.

164 THE NETTER COLLECTION OF MEDICAL ILLUSTRATIONS