Chancroid
Chancroid is an acute sexually transmitted infection (STI) caused by the gram-negative bacillus Haemophilus ducreyi. In sharp contrast to the firm, painless chancre of primary syphilis (Treponema pallidum), chancroid is known for soft, deep, ragged genital ulcers that are extremely painful, often accompanied by swollen, pus-filled lymph nodes in the groin (a chancroidal bubo).
Although chancroid has become less common in many developed countries thanks to widespread use of broad-spectrum antibiotics, it remains common in tropical and subtropical regions. It is also one of the leading risk factors for HIV transmission, raising the risk 5–10-fold, because it breaks down the genital mucosal barrier and draws large numbers of CD4+ T cells into the necrotic, inflamed tissue.
At Haute-Derma, chancroid is handled through an urgent STI differential-diagnosis pathway: multiplex real-time PCR, direct Gram stain microscopy, ultrasound-guided aspiration of affected lymph nodes, and single-dose bactericidal antibiotic regimens in line with WHO/CDC guidelines. The aim is to stop the pain quickly, prevent persistent draining sinuses, and restore the appearance of any scars after treatment.
Pathogenesis: How H. ducreyi Causes Necrotic Inflammation
Bacterial Features and Cell Toxins
- Haemophilus ducreyi is a small, facultatively anaerobic gram-negative coccobacillus that needs factor X (hemin) to grow.
- It releases cytolethal distending toxin (CDT), which halts the cell cycle at the G2/M phase, causing abnormal keratinization and widespread death of epidermal and mucosal cells.
- Surface and outer membrane proteins (LspA1, LspA2) help H. ducreyi resist being engulfed by neutrophils and macrophages in the local tissue.
Recruitment of Inflammatory Cells and Ulcer Formation
- Bacteria entering through tiny abrasions provoke a vigorous immune response, drawing in polymorphonuclear neutrophils (PMNs) and CD4+ T cells.
- Micro-abscesses form in the epidermis, the lining breaks down, and a shallow necrotic ulcer develops that gradually deepens. Because there is none of the fibrous thickening or vascular sclerosis seen in syphilis, the base of the ulcer is completely soft (a "soft sore") yet extremely sensitive to pain.
Clinical Features and Variants
Typical Course
- Incubation period: Very short, just 3–7 days (rarely more than 10 days) after unprotected sex.
- Initial lesion: A red papule that quickly turns into a pustule on a red base.
- Chancroid ulcer: The pustule breaks open after 24–48 hours, leaving an ulcer with these features:
- Appearance: The base is covered with a yellow-gray necrotic, purulent membrane that bleeds very easily when touched; the edges are ragged, surrounded by a red rim, and undermined.
- Sensation: Severe, stabbing pain that worsens on contact with urine or rubbing from clothing.
- Location: In men, usually the frenulum, coronal sulcus or foreskin; in women, the labia majora, labia minora, vaginal vestibule or around the anus.
Groin Node Complication (Chancroidal Bubo)
- Develops in about 50% of patients, 1–2 weeks after the first ulcer appears.
- The nodes are usually on one side only (unilateral), large and painful, with hot, red overlying skin.
- Without treatment, the node becomes fixed to the surrounding tissue, softens in the center as pus forms, and bursts through the skin, leaving a sinus that drains thick, chocolate-colored pus, a deep groin ulcer that is slow to heal, and thick hypertrophic scarring.
Telling Genital Ulcers Apart
| Chancroid (H. ducreyi) | Primary Syphilis Chancre (T. pallidum) | Genital Herpes (HSV-1/2) |
|---|---|---|
| VERY PAINFUL, tender | PAINLESS, not itchy | Burning, stinging, itchy |
| Soft, dirty base covered with pus, bleeds easily | Firm like cartilage, clean base, no pus | Shallow, from clusters of ruptured blisters |
| Ragged, undermined edges | Sharp, regular borders | Scalloped, with old and new blisters |
| One-sided groin nodes that suppurate and drain | Two-sided groin nodes, firm, no pus | Two-sided groin nodes, small, mildly tender |
| Incubation 3–7 days | Incubation 10–90 days (average 3 weeks) | Incubation 2–12 days |
How Chancroid Is Diagnosed at Haute-Derma
Gram Stain of Ulcer Exudate:
- The sample is taken from the edge or cleaned base of the ulcer, avoiding surface pus.
- It shows small gram-negative bacilli lined up in parallel chains, the characteristic "school of fish" or "railroad track" pattern. However, sensitivity is only 40–60%.
Multiplex Real-Time PCR for STIs: The modern gold-standard method used at Haute-Derma. It amplifies specific gene sequences of H. ducreyi together with T. pallidum and HSV-1/2 from a single ulcer swab, giving accurate results even when bacterial numbers are low or several infections are present at once.
Mandatory Screening for Co-Infections and Exclusion of Other Causes:
- Dermoscopy of the ulcer edge to assess necrotic small vessels.
- Required tests: syphilis serology (RPR/TPHA), HIV Ag/Ab combination test, and PCR swabs for Chlamydia and Neisseria gonorrhoeae.
Treatment and Urgent Management at Haute-Derma
Standard Antibiotic Regimens (CDC / WHO Guidelines)
Our doctors prescribe one of the following four preferred regimens, depending on the patient's overall health and any drug allergies:
- Regimen 1 (preferred single dose): azithromycin 1 g by mouth as a single dose.
- Regimen 2 (preferred injection): ceftriaxone 250 mg by deep intramuscular injection as a single dose.
- Regimen 3 (alternative): ciprofloxacin 500 mg by mouth twice daily for 3 consecutive days (contraindicated in pregnancy, breastfeeding and patients under 18).
- Regimen 4 (for pregnant women): erythromycin 500 mg by mouth three times daily for 7 days.
Managing Suppurative Groin Nodes (Bubo Management)
- Large-bore needle aspiration: Performed under superficial ultrasound guidance. The doctor passes the needle through nearby healthy skin into the center of the abscess and drains the necrotic fluid completely, relieving pressure immediately and preventing spontaneous rupture.
- OPEN INCISION AND DRAINAGE IS CONTRAINDICATED: Cutting open a chancroidal bubo spreads the bacteria further, leading to a huge, slow-healing groin ulcer and severe contracting scars.
Partner Treatment and Cosmetic Repair of Genital Skin
- Partner management: Anyone who had sexual contact with the patient in the 10 days before symptoms began must be examined and given preventive antibiotics, whether or not they have symptoms.
- Cosmetic tissue regeneration at Haute-Derma: Once the bacteria have been eradicated (ulcers improve within 3–7 days), deep genital ulcers and node aspiration sites are treated with EGF/FGF regenerative solutions combined with LED light therapy (633 nm red light) to speed re-epithelialization and minimize the risk of depressed or hypertrophic scars.
