What is chancroid?

Definition

Chancroid is a sexually transmitted disease (STD) caused by the bacterium
Haemophilus ducreyi. The disease, which causes painful sores on
the genitalia, is most common in developing countries. Chancroid increases the
risk of infection by other sexually transmitted pathogens,
including the human immunodeficiency virus.

Causes

Chancroid is caused by H. ducreyi, a sexually transmitted,
gram-negative, facultatively anaerobic, coccobacillus. The bacterium grows in
chains and requires hemin for growth. The bacterium needs breaks in the host’s
epidermal layer to initiate infection.

Risk Factors

Chancroid is more common in uncircumcised males and in persons who have sex with sex workers in developing countries.

Symptoms

The initial appearance after infection is a reddened, raised lesion on the
genitalia three to five days after exposure, although the infection can appear in
as little as one day or in as many as fourteen days. Within twenty-four hours, the
lesion converts to a painful, soft-edged ulcer with irregular borders that often
secrete pus. Men often have a single ulcer and women usually have four or
more.

Swollen, painful lymph nodes are also present in approximately one-half of
cases. These swollen nodes, called buboes, may rupture and form abscesses
that drain pus. Women tend to have milder symptoms than men, and more than 50
percent of infected women are asymptomatic. Self-inoculation with the fingers can
transfer the bacteria, so that chancroid ulcers appear at other locations on the
body, especially on the conjunctiva, a membrane that covers the eye and lines the
inner surface of the eyelid.

Screening and Diagnosis

Chancroid can be confused with the hard chancre of syphilis, but
chancre, unlike chancroid, is usually painless, does not
exude pus, and heals on its own within six weeks. Samples from a skin ulcer can
also be looked at with dark-field microscopy; a lack of visible spirochetes
indicates chancroid rather than a syphilitic chancre. Definitive diagnosis depends
on isolating the bacteria and growing it on one of three specialized media,
although this test is only 80 percent effective in diagnosis.

Treatment and Therapy

Chancroid responds well to antibiotics. The most common regimen is
a single dose of azithromycin. Other possible treatments include a single
intramuscular injection of ceftriaxone, oral ciprofloxacin twice daily for three
days, or erythromycin four times a day for a week. Infections in uncircumcised
males are more resistant to antibiotic therapy. Sex partners of infected persons
are also treated, even if they show no signs of chancroid.

Prevention and Outcomes

The use of latex condoms decreases the likelihood of infection. Infection does not cause lasting immunity, and no effective immunizations have been developed.

Bibliography

Klausner, Jeffrey D., and Edward W. Hook III. Current Diagnosis and Treatment of Sexually Transmitted Diseases. New York: McGraw-Hill, 2007.

Larsen, Laura. Sexually Transmitted Diseases Sourcebook. Detroit: Omnigraphics, 2009.

Murphy, T. F. “Haemophilis Infections.” In Mandell, Douglas, and Bennett’s Principles and Practice of Infectious Diseases, edited by Gerald L. Mandell, John E Bennett, and Raphael Dolin. 7th ed. New York: Churchill Livingstone/Elsevier, 2010.

Spinola, Stanley M., Margaret E. Bauer, and Robert S. Munson, Jr. “Immunopathenogenesis of Haemophilus ducreyi Infection (Chancroid).” Infection and Immunity 70 (2002): 1667-1676.

Workowski, Kimberly A., and Stuart M. Berman. “Diseases Characterized by Genital Ulcers.” Morbidity and Mortality Weekly Report 55 (2006): 14-30.