Lymphadenitis is a topic covered in the 5-Minute Emergency Consult.

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  • Lymph nodes may be swollen and tender as part of the systemic response to infection:
    • Become engorged with lymphocytes and macrophages
    • May be primarily infected
    • Infection in distal extremity may result in painful tender adenopathy proximally
  • Acute suppurative lymphadenitis may occur after pharyngeal or skin infection


  • Most frequently caused by bacterial infection
  • Most common organisms in pyogenic lymphadenitis:
    • Staphylococcus aureus—including resistant strains such as community-associated methicillin-resistant S. aureus (CA-MRSA):
      • CA-MRSA risk factors include prior MRSA infection, household contact of CA-MRSA patient, military personnel, incarcerated persons, athletes in contact sports, IV drug users, men who have sex with men
      • Different antibiotic susceptibility than nosocomial MRSA
      • CA-MRSA now sufficiently prevalent to warrant coverage in empiric treatment
      • Suspect CA-MRSA in unresponsive infections
    • Group A β-hemolytic Streptococcus
  • Cervical lymphadenitis:
    • Usually pharyngeal or periodontal process
    • Streptococcus and anaerobes
  • Axillary lymphadenitis:
    • Streptococcus pyogenes (group A β-hemolytic Streptococcus)
  • Nosocomial MRSA:
    • Risk factors: Recent hospital or long-term care admission, surgery, injection drug use, vascular catheter, dialysis, recent antibiotic use, unresponsive infection
    • Resistant to most antibiotics (see “Treatment”)

Pediatric Considerations
  • Acute unilateral cervical suppurative lymphadenitis:
    • Most common at age <6 yr
    • Group A Streptococcus, S. aureus, and anaerobes are most common causes

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