PATHOGENS

• Staphylococci account for >50% of total prosthetic joint infections (PJI). Gram negatives may account for 15%. Approximately 20% may be polymicrobial.
• Culture-negative infections represent ~7-11% of infections; some may be due to prior abx therapy.
• Bacterial:
  
  • Staphylococcus (coagulase-negative)
  • Staphylococcus aureus 
  • Viridans streptococci 
  • Cutibacterium acnes (especially shoulder implant infections, formerly Propionibacterium)
  • Enterococcal species
  • Gram-negative enteric bacteria
  • Pseudomonas aeruginosa
  • Anaerobes
  • Brucella spp (rare)
• Mycobacterial:
  • Non-tubercular mycobacteria (rare)
  • M. tuberculosis (very rare)
• Fungal:
  • Candida species
• Typical pathogens by the time of onset following prosthesis placement:
  
  • Early infection (0-3 months post-op): predominantly S. aureus, β-hemolytic streptococci, Gram-negative bacilli, polymicrobial infection, anaerobic
  • Delayed (3 mos-2 yrs): usual pathogens include coagulase-negative Staphylococci,S. aureus,C. acnes, Enterococcus spp.
  • Late (>2 yrs): S. aureus, coagulase-negative Staphylococci, viridans Streptococci, Enterococci, C. acnes
    • Less common: Gram-negatives