Differential Diagnosis for IVDU with Sepsis and BLE Eschars

• Single Most Likely Diagnosis
  • Endocarditis with septic emboli: This is a common complication in intravenous drug users (IVDU) due to the introduction of bacteria into the bloodstream, which can lead to infection of the heart valves and subsequent embolization to peripheral sites, including the skin, resulting in eschars.
• Other Likely Diagnoses
  • Cellulitis or abscess: Skin infections are common in IVDU and can present with eschars, especially if there is a history of injecting into the affected limb.
  • Necrotizing fasciitis: A severe infection of the skin and subcutaneous tissue that can result from bacterial infection, often seen in the context of trauma or injection drug use.
  • Osteomyelitis: Bone infection that can occur from direct inoculation during injection or from hematogenous spread, potentially causing systemic symptoms like sepsis.
• Do Not Miss Diagnoses
  • Methicillin-resistant Staphylococcus aureus (MRSA) infection: MRSA is a common cause of skin and soft tissue infections in IVDU and can lead to severe disease, including sepsis and necrotizing fasciitis.
  • Gas gangrene (Clostridial myonecrosis): A rapidly progressive and potentially fatal infection that can occur after traumatic injury or injection, characterized by necrosis of muscle tissue.
  • Tetanus: Although less common, tetanus infection can occur in IVDU, especially if they have not been vaccinated, and can present with systemic symptoms including rigidity and spasms.
• Rare Diagnoses
  • Fungal infections (e.g., Candida): While less common than bacterial infections, fungal infections can occur in IVDU, particularly in those with compromised immune systems or who use contaminated needles.
  • Viridans streptococcal endocarditis: Though more commonly associated with dental procedures, this type of endocarditis can also occur in IVDU, especially if they have poor dental hygiene or other risk factors.