What are the causes of skin and soft tissue infection (SSTI)?

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Last updated: March 12, 2025View editorial policy

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Differential Diagnosis for Skin Soft Tissue Infection

  • Single Most Likely Diagnosis
    • Cellulitis: This is the most common skin and soft tissue infection, characterized by redness, warmth, swelling, and pain in the affected area. It is often caused by streptococcal or staphylococcal bacteria.
  • Other Likely Diagnoses
    • Abscess: A localized collection of pus that can occur in any skin or soft tissue, often caused by Staphylococcus aureus.
    • Folliculitis: An infection of the hair follicles, typically caused by Staphylococcus aureus, presenting with small, pus-filled bumps.
    • Furuncle (Boil): A deeper infection of the hair follicle and surrounding tissue, also usually caused by Staphylococcus aureus.
  • Do Not Miss Diagnoses
    • Necrotizing Fasciitis: A severe infection that destroys the tissue under the skin, including fat and the tissue covering the muscles (fascia). It is a medical emergency and can be deadly if not promptly treated.
    • Gas Gangrene: A potentially deadly infection caused by Clostridium perfringens, characterized by gas production in the tissues, leading to tissue death.
    • Erysipelas: A type of skin infection that involves the upper layer of the skin and can spread rapidly, often caused by streptococcal bacteria.
  • Rare Diagnoses
    • Ecthyma: A variant of impetigo that extends into the dermis, causing shallow ulcerations.
    • Actinomycosis: A rare chronic infection caused by Actinomyces bacteria, which can affect the skin and soft tissues, among other areas.
    • Mycobacterial infections (e.g., Mycobacterium tuberculosis, M. leprae): Though more commonly associated with systemic or pulmonary disease, these bacteria can cause skin and soft tissue infections, especially in immunocompromised individuals.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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