Chancroid is infection of the genital skin or mucous membranes caused by Haemophilus ducreyi
(See also Overview of Sexually Transmitted Infections.)
Haemophilus ducreyi is a short, slender, gram-negative bacillus with rounded ends.
Chancroid is a rare sexually transmitted infection (STI) in the US and other resource-rich countries, occurring primarily in occasional, local epidemics. Chancroid is a common cause of genital ulcers in resource-poor areas of Asia, Africa, and the Caribbean. Like other STIs causing genital ulcers, chancroid increases risk of HIV transmission.
H. ducreyi may also cause nongenital skin ulcers in children and adults, which has been reported in countries of the South Pacific region and Indonesia (1, 2).
General references
1. Mitjà O, Lukehart SA, Pokowas G, et al: Haemophilus ducreyi as a cause of skin ulcers in children from a yaws-endemic area of Papua New Guinea: A prospective cohort study. Lancet Glob Health 2:e235–41, 2014. doi: 10.1016/S2214-109X(14)70019-1
2. van Hattem JM, Langeveld TJC, Bruisten SM, et al: Haemophilus ducreyi cutaneous ulcer contracted at Seram Island, Indonesia, presented in the Netherlands. PLoS Negl Trop Dis 12(4):e0006273, 2018. doi: 10.1371/journal.pntd.0006273
Symptoms and Signs of Chancroid
After an incubation period of 3 to 7 days, small, painful papules appear on the genitals and rapidly break down into shallow, soft, painful ulcers with ragged, undermined edges (ie, with overhanging tissue) and a red border. Ulcers vary in size and often coalesce. Deeper erosion occasionally leads to marked tissue destruction.
The inguinal lymph nodes form a bubo (enlarged and tender group of regional lymph nodes). They sometimes become matted together, fluctuant, or suppurative, in some cases forming an abscess. The skin over the abscess may become red and shiny and may break down to form a sinus. The infection may spread to other areas of skin, resulting in new lesions. Phimosis, urethral stricture, and urethral fistula may result from chancroid.
Image courtesy of Dr. Pirozzi via the Public Health Image Library of the Centers for Disease Control and Prevention.
Diagnosis of Chancroid
History and physical examination
Sometimes culture or polymerase chain reaction (PCR)
Chancroid is suspected in patients who have unexplained genital ulcers or buboes (swollen, tender lymph nodes that may become suppurative or form abscesses) and who are or have been in endemic areas. Genital ulcers from other causes (see table Differentiating Common Sexually Transmitted Genital Lesions) may resemble chancroid.
Diagnosis is usually based on clinical findings alone because culture of the bacteria is difficult and microscopic identification is confounded by the mixed flora in ulcers.
If available, a sample of pus from a bubo or exudate from the edge of an ulcer should be sent to a laboratory that can identify H. ducreyi. PCR testing is not commercially available, but several institutions have certified tests that are highly sensitive (98.4%) and specific (99.6%) for H. ducreyi. Clinical diagnosis has a lower sensitivity (53 to 95%) and specificity (41 to 75%).
Serologic testing for syphilis and HIV and cultures for herpes should be done to exclude other causes of genital ulcers. However, interpretation of test results is complicated by the fact that genital ulcers due to other conditions may be coinfected with H. ducreyi.
Treatment of Chancroid
Antibiotics (various)
Treatment of chancroid should be started promptly, without waiting for test results. One of the following is recommended:
Patients treated for other causes of genital ulcers should be given antibiotics that also treat chancroid if chancroid is suspected and laboratory testing is impractical.
Treatment of patients with HIV coinfection, particularly with single-dose regimens, may be ineffective. In these patients, ulcers may require up to 2 weeks to heal, and lymphadenopathy may resolve more slowly.
Buboes can safely be aspirated for diagnosis or incised for symptomatic relief if patients are also given effective antibiotics.
Sex partners should be examined and treated if they had sexual contact with the patient during the 10 days before the patient’s symptoms began.
Patients with chancroid should have a serologic test for syphilis and HIV 3 months after being diagnosed with chancroid.
