Multiple sinuses from infection of great toe is mainly caused by:September 2007

Ans. B: ActinomycetesMycetoma is a chronic localized granulomatous inflammatory lesion common in the tropics and sub-tropics.Multiple siAuses, soft tissue swelling and discharge of coloured granules characterize a mycetoma foot. Chronic sinuses discharging granules are caused by (1) Eumycetes (true fungi), (2) Schizomycetes, which includesActinomycosis (aerobic higher filamentous bacteria) andBotryomycosis (bacterial infection).- Actinomycosis is often caused by Actinomadura or Nocardia species wherein it gains entry after penetrating trauma (splinter, gravel or thorn prick).Young males are commonly affected and 75% of the lesions occur in the lower limbs.The disease slowly progresses from a nodule to multiple sinuses discharging coloured granules. Involvement of bone is late following dermal and soft tissue spread.- Botryomycosis (a misnomer), a chronic suppurative infection is caused by bacteria involving skin or viscera . This rare condition mimics a deep mycotic infection and is often caused by Staphylococcus or Pseudomonas species of bacteria. The feet and hands are commonly affected and penetrating trauma may be a predisposing factor. It usually presents as a nodule, sinus or ulcer, which is initially localized.The diagnosis of actinomycosis is based on clinical findings, demonstration of characteristic granules and culture of the organism from a deep tissue biopsy.Immunological studies (counter immuno electrophoresis and ELISA) are also used. Botryomycosis is diagnosed based on a positive gram's stain and culture; negative fungal cultures and demonstration of the characteristic botryomycotic granules at histopathology from a deep biopsy.In endemic areas, subcutaneous swelling with sinuses should be considered as mycetoma unless proved otherwise. The differential diagnosis includes chronic osteomyelitis, tuberculosis and chronic abscesses.