January 15, 2025

A 62-year-old man with history of type 2 diabetes mellitus

By Med-Challenger · 1 minute read

A 62-year-old man with history of type 2 diabetes mellitus requiring insulin presents after returning from a trip to Colombia.

Two weeks before hospital admission the patient developed daily fevers, diminished appetite, diffuse myalgias, mild shortness of breath, headache, and backache. Two days before admission he developed pain in the right thigh. On examination, the patient was febrile, tachycardic, and exhausted. The examination of his lungs, heart, and abdomen was unrevealing. His right thigh was tender to touch, although there was no frank erythema or swelling.

The patient’s white cell count was 20.6 × 109 cells/L, hemoglobin 10.6 mg/dL, glucose 323 mg/dL, sedimentation rate 100 mm/hour, and creatine kinase 745 U/L. Magnetic resonance imaging showed fluid collection affecting the vastus lateralis muscle (see figure).

image (61) Figure.

The most likely cause of this infection is which of the following?

Streptococcus pneumoniae
Salmonella species
Streptococcus anginosus
Staphylococcus aureus
Anaerobes

The correct answer is:

Staphylococcus aureus

The patient has pyomyositis, which is an infection characterized by the subacute formation of an abscess in the muscle. The initial phase of the disease may have unspecific symptoms, with localized symptoms of pain and swelling appearing later in the course of infection. This condition is also called primary pyomyositis or tropical pyomyositis because it is common in warm climates; however, it has also been described in temperate climates, particularly among patients who are immunocompromised or in those with diabetes. Trauma may or may not precede the disease. S. aureus is the most common etiologic agent, although S. anginosus, S. pneumonia, Salmonella species, and anaerobes have also been described. Drainage and antibiotics are the treatment of choice.

References:

Crum NF. Bacterial pyomyositis in the United States. Am J Med. 2004;117(6):420-428.

Gibson RK, Rosenthal SJ, Lukert BP. Pyomyositis. Increasing recognition in temperate climates. Am J Med. 1984;77(4):768-772.

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