History:

 This patient was immunosuppressed with myelofibrosis. He injured his finger on a bush in the garden and within 24 hours had a painful swelling on his finger with a high fever. Blood cultures and a local swab were negative but the organism was grown from the tissue biopsy sent for histology and culture and from a swab of the biopsy base. He was treated with Ciproxin and Bactrim. 

Serratia marcescens is a gram neg bacillus present in both soil and water. Most cases of severe infection are seen in immunosuppressed individuals. It may involve blood vessels causing a vasculopathy and skin necrosis.

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