Chancroid

Chancroid (also known as soft chancre) is a highly contagious sexually transmitted infection (STI) caused by Haemophilus ducreyi. Although chancroid is a rare infection in the US, it may occur in immunocompromised patients and is a common cause of genital ulcers in tropical and subtropical regions. It is characterized by the formation of small, painful ulcers on the genitalia and regional lymphadenopathy. The diagnosis is primarily based on clinical findings and is probable if genital herpes and syphilitic chancre have been ruled out. Culture confirms the diagnosis but is not widely available. Treatment usually involves administration of an antibiotic such as ceftriaxone or azithromycin.

• Pathogen: Haemophilus ducreyi
• Transmission: sexually transmitted infection

• Incubation period: typically 4–10 days
• Clinical features
  • Very painful genital ulcers
    • ♂: glans penis, penis shaft, and scrotum
    • ♀: vulva and perineal area
  • Deep, small (∼ 10–20 mm in diameter), well-demarcated lesions with a grayish necrotic base
  • Painful inguinal lymphadenopathy ^[3]
  • An asymptomatic course is more likely in women.

In contrast to chancre, chancroid is often painful: The causative pathogen is Haemophilus du-creyi ("do cry")!

References:^[4][5]

• Diagnostic criteria for chancroid: A probable diagnosis of chancroid can be made if all the following criteria are met. ^[1]
  • Presence of painful deep genital ulcers and tender lymphadenopathy
  • Negative tests for T. pallidum (see “Diagnostics for syphilis”)
  • Negative tests for HSV1 and HSV2 (see “Diagnostics for genital herpes”).
• Confirmatory studies: rarely performed ^[1]
  • Gram-stain: gram-negative rods in ulcer exudate (swab sample) suggestive of Haemophilus ducreyi infection
  • Culture : Consider in areas where chancroid is highly prevalent. ^[1][2]
  • NAAT

Chancroid is a nationally notifiable disease in the United States. Report all cases to the local or state health department. ^[6]

• See differential diagnosis of other genital lesions.

The differential diagnoses listed here are not exhaustive.

• Antibiotics for chancroid ^[1]
  • Single-dose therapy with azithromycin OR ceftriaxone ^[1]
  • OR multidose therapy with ciprofloxacin OR erythromycin base ^[1]
• Follow-up in 3–7 days.
  • No improvement : Consider alternative diagnoses, treatment resistance, or HIV coinfection.
  • Persistent fluctuant lymphadenopathy may require drainage.
• Trace and treat all partners within 10 days prior to symptom onset: See "Management of sexual partners." ^[1]

Symptoms may take longer to resolve in uncircumcised patients and those with HIV. ^[1]