Fusobacteria - Tropical ulcer
Tropical ulcer is a necrotising skin infection occurring in hot, humid climates. Fusobacterium species are almost always present, though other mixed anaerobes may contribute. Common in barefoot populations and in areas with poor hygiene or minor skin trauma.
🧬 Aetiology
- Initiated by minor trauma or insect bites → secondary infection with Fusobacteria and other anaerobes.
- Malnutrition and poor living conditions increase susceptibility.
- May coexist with spirochaetes or other tropical pathogens.
🩺 Clinical Features
- Intensely painful, rapidly enlarging shallow ulcer.
- Typically found on the lower limb (ankle, shin, foot).
- More common in children and young adults in tropical regions.
- If untreated → chronicity, deep tissue destruction, and risk of secondary osteomyelitis.
🔍 Differentials
- Cutaneous leishmaniasis.
- Atypical mycobacterial infection.
- Pyoderma gangrenosum.
- Venous or arterial leg ulcers.
- Yaws (Treponema pallidum pertenue).
🧪 Investigations
- Swabs and cultures from ulcer base and edges → bacterial identification.
- Biopsy if diagnosis uncertain (to exclude atypical infections or malignancy).
- Blood tests: FBC, CRP if systemic infection suspected.
💊 Management
- Antibiotics: Tetracycline and/or Metronidazole (targeting anaerobes).
- Local care: wound cleaning, dressings, and limb elevation.
- Surgical debridement to remove necrotic tissue.
- Skin grafting may be required in extensive cases.
- Nutritional support and public health interventions (footwear, hygiene) help prevention.
📚 References
🧾 Clinical Case – Tropical Ulcer (Fusobacteria)
A 19-year-old man from rural West Africa presents with a painful ulcer on his lower leg that began as a pustule two weeks earlier.
On examination, there is a deep ulcer with undermined edges and foul-smelling discharge.
He is otherwise systemically well.
Swab culture grows Fusobacterium mixed with other anaerobes.
👉 Diagnosis: Tropical ulcer due to polymicrobial infection (Fusobacteria prominent).
👉 Management: wound debridement, oral metronidazole plus broad-spectrum antibiotics, improved nutrition, and hygiene measures.
