Saturday, December 27, 2014

A 42-year-old man with poorly controlled diabetes (HbA1c, 13.3%) presents with thigh pain and fever over several weeks.

A 42-year-old man with poorly controlled diabetes (HbA1c, 13.3%) presents with thigh pain and fever over several weeks.



Physical examination reveals erythema and warmth over the thigh with notable woody, nonpitting
edema. There are no cutaneous ulcers. CT of the thigh reveals several abscesses located between the muscle fibers of the thigh. Orthopedics is consulted to drain and culture the abscesses.

Which of the following is the most likely pathogen?

A. Clostridium perfringens
B. Group A streptococcus
C. Polymicrobial flora
D. Staphylococcus aureus
E. Streptococcus milleri

The answer is D.  

This patient has infectious pyomyositis, a disease of the tropics and of immunocompromised hosts such as patients with poorly controlled diabetes mellitus or AIDS. The pathogen is usually Staphylococcus aureus. Management includes aggressive debridement, antibiotics, and attempts to reverse the patient’s immunocompromised status.

 Clostridium perfringens may cause gas gangrene, particularly in devitalized tissues. Streptococcal infections may cause cellulitis or an aggressive fasciitis, but the presence of abscesses in a patient with poorly controlled diabetes makes staphylococcal infection more likely.

Polymicrobial infections are common in diabetic ulcers, but in this case, the imaging and physical examination show intramuscular abscesses.

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