Septic Arthritis: The Daily PANCE Blueprint

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Septic Arthritis: The Daily PANCE Blueprint

A 35-year-old man with a history of intravenous drug use presents to the emergency department with a two-day history of severe pain, swelling, and redness in his left knee. He also reports fever and chills. On examination, his temperature is 38.7°C (101.7°F), and his left knee is erythematous, warm, and markedly tender with a limited range of motion. Arthrocentesis reveals purulent synovial fluid with a white blood cell count of 95,000/mm³ and 92% neutrophils. What is the most likely causative organism of this patient's condition?

A. Borrelia burgdorferi
B. Staphylococcus aureus
C. Neisseria gonorrhoeae
D. Pseudomonas aeruginosa
E. Streptococcus pyogenes

Answer and topic summary

The answer is D. Pseudomonas aeruginosa

Pseudomonas aeruginosa is a common causative organism of septic arthritis in intravenous drug users. The introduction of bacteria through non-sterile injection practices increases the risk of infection with organisms like Pseudomonas. The patient’s presentation of acute monoarticular arthritis with systemic symptoms and the background of IV drug use strongly suggest Pseudomonas aeruginosa.

  • Staphylococcus aureus is responsible for 40-50% of cases
  • Neisseria gonorrhea in sexually active young adults
  • Pseudomonas in IV drug abusers
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Smarty PANCE Content Blueprint Review:

Covered under ⇒ PANCE Blueprint Musculoskeletal ⇒ Infectious Diseases ⇒ Septic arthritis

Also appears on the Emergency Medicine content blueprint for EOR exams

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