Escherichia coli can cause pyomyositis in susceptible patients.
Clinical features of the pyomyositis:
(1) fever
(2) pain and tenderness of the affected muscle
(3) hypotension, especially if septic
A CT scan or MRI will show edema in the muscle.
Clinical stages of pyomyositis:
(1) Stage 1: evolving inflammation without aspiratable pus
(2) Stage 2: frank abscess
(3) Stage 3: systemic toxicity
A patient with impaired host defenses may quickly deteriorate in Stage 3, requiring intensive care.
Risk factors for pyomyositis:
(1) presence of an underlying hematologic malignancy
(2) other cause for immunosuppression (high dose corticosteroid therapy, etc)
(3) infection with E.coli strain ST131 (O25:H4), which is extended spectrum beta-lactamase producing and fluoroquinolone-resistant
(4) febrile neutropenia
