Haemophilus ducreyi – Chancroid Pathogen Explained
Haemophilus ducreyi is a gram-negative bacterium and the causative agent of chancroid, a sexually transmitted infection characterized by painful genital ulcers and swollen lymph nodes.
Wissenswertes über "Haemophilus ducreyi"
Haemophilus ducreyi is a gram-negative bacterium and the causative agent of chancroid, a sexually transmitted infection characterized by painful genital ulcers and swollen lymph nodes.
What is Haemophilus ducreyi?
Haemophilus ducreyi is a gram-negative, rod-shaped bacterium belonging to the family Pasteurellaceae. It is the causative agent of chancroid, also known as soft chancre or ulcus molle. Chancroid is a sexually transmitted infection (STI) that occurs worldwide but is most prevalent in tropical and subtropical regions of Africa, Asia, and Latin America.
Transmission and Risk Factors
Haemophilus ducreyi is transmitted exclusively through direct skin-to-skin or mucous membrane contact, typically during unprotected sexual intercourse. The bacterium enters the body through small abrasions or microtraumas in the skin or mucous membranes.
- Unprotected sexual intercourse with an infected person
- Multiple sexual partners
- Pre-existing skin lesions in the genital area
- Living in or traveling to endemic regions (tropical and subtropical areas)
- Limited access to healthcare and hygiene resources
Symptoms
Clinical signs of chancroid typically appear 3 to 7 days after infection. Unlike the hard chancre of syphilis, the ulcers caused by Haemophilus ducreyi are characteristically painful.
- Painful genital ulcers with soft, irregular, and undermined edges
- Ulcers with a yellowish-gray necrotic base that bleeds easily
- Redness and swelling of the surrounding skin
- Buboes: painful inguinal lymph node swelling (present in approximately 50% of cases)
- General malaise and fever in severe cases
Diagnosis
Diagnosis of Haemophilus ducreyi infection relies on clinical presentation as well as microbiological and molecular testing. Co-infection with other STIs must be excluded.
Clinical Diagnosis
The characteristic appearance of the ulcers often allows a presumptive clinical diagnosis. It is essential to differentiate chancroid from other genital ulcer diseases, particularly syphilis (caused by Treponema pallidum) and genital herpes (caused by herpes simplex virus).
Laboratory Diagnosis
- Culture: growth of the bacterium on specialized media (e.g., GC agar with supplements); considered the gold standard but technically challenging
- PCR (polymerase chain reaction): highly sensitive and specific detection of bacterial DNA from swab specimens
- Gram stain and microscopy: characteristic appearance of chains of small gram-negative rods
- Serological testing to rule out concurrent syphilis and HSV infection is strongly recommended
Treatment
Chancroid responds well to antibiotic therapy when diagnosed promptly. Early treatment prevents complications such as extensive ulceration and lymph node abscess formation.
Recommended Antibiotic Regimens
- Azithromycin: 1 g orally as a single dose (preferred first-line therapy)
- Ceftriaxone: 250 mg intramuscularly as a single dose
- Ciprofloxacin: 500 mg orally twice daily for 3 days (contraindicated in pregnancy)
- Erythromycin base: 500 mg orally three times daily for 7 days
Sexual partners of infected individuals should also be evaluated and treated if necessary, even in the absence of symptoms. Consistent condom use significantly reduces the risk of transmission.
Complications
If left untreated, Haemophilus ducreyi infection can lead to serious complications:
- Extensive, necrotizing ulceration
- Inguinal bubo formation with spontaneous rupture and abscess drainage
- Significantly increased risk of HIV acquisition and transmission due to disrupted skin and mucosal barriers
- Phimosis or paraphimosis in male patients as a result of scarring
Prevention
- Consistent use of condoms during sexual activity
- Regular STI screening for individuals at higher risk
- Sexual health education and awareness
- Early treatment and partner notification
References
- World Health Organization (WHO): Guidelines for the Management of Sexually Transmitted Infections. WHO Press, Geneva, 2003 (updated recommendations available at who.int).
- Lewis DA. Chancroid: clinical manifestations, diagnosis, and management. Sexually Transmitted Infections. 2003;79(1):68-71. PubMed PMID: 12576620.
- Centers for Disease Control and Prevention (CDC): Sexually Transmitted Infections Treatment Guidelines, 2021 -- Chancroid. Available at cdc.gov/std.
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Related search terms: Haemophilus ducreyi + Haemophilus Ducreyi + H. ducreyi