A Common Infection From an Unexpected Culprit: Metatarsal Osteomyelitis Caused by Streptococcus milleri in a Patient With Type 3c Diabetes

A male patient in his late 40s presented to the emergency department of an academic, tertiary medical center with a malodorous, full-thickness ulceration on the lateroplantar aspect of his right foot, exposing the fifth metatarsal head. He was also found to be in a hyperosmolar hyperglycemic state with a blood glucose level of 628 mg/dL (reference range: 70-100 mg/dL) secondary to uncontrolled pancreatogenic (type 3c) diabetes mellitus (T3cDM). Cultures from a bedside biopsy performed by our podiatry service grew <i>Streptococcus milleri</i> (<i>S. milleri</i>) and unidentified anaerobes. Despite early and broad-spectrum intravenous antibiotics, a partial fifth ray amputation with fillet toe flap was necessitated and performed without complication. With source control demonstrated by negative surgical margins, our patient was downgraded to a five-day course of oral amoxicillin-clavulanate and discharged two days after amputation. Our patient's case supports the notion that <i>S. milleri</i>, a commensal bacterium of the gastrointestinal (GI) and genitourinary (GU) tracts, may have an underappreciated ability to cause skin and musculoskeletal infections in the setting of severely elevated blood glucose levels.