Prosthetic Joint Infections Joseph P. Myers, MD, FACP, FIDSA Chair, Department of Medicine Summa Akron City/St. Thomas Hospitals Professor of Internal Medicine and Master Teacher Northeastern Ohio Medical University Pre-Test Question No. 1 1. What is the most common class of micro-organisms causing prosthetic joint infections? a. Aerobic Gram-negative bacilli (e.g. Pseudomonas) b. Anaerobic Gram-negative bacilli (e.g. Bacteroides) c. Anaerobic Gram-positive bacilli (e.g. Clostridium) d. Aerobic Gram-positive cocci (e.g. Staphylococcus) e. Amaerobic Gram-positive cocci (e.g. Peptococcus) Pre-Test Question No. 1 1. What is the most common class of micro-organisms causing prosthetic joint infections? a. Aerobic Gram-negative bacilli (e.g. Pseudomonas) b. Anaerobic Gram-negative bacilli (e.g. Bacteroides) c. Anaerobic Gram-positive bacilli (e.g. Clostridium) d. Aerobic Gram-positive cocci (e.g. Staphylococcus) e. Amaerobic Gram-positive cocci (e.g. Peptococcus) Pre-Test Question No. 2 2. What is the most important pathogenic mechanism for organisms causing prosthetic joint infection? a. α - haemolysin b. Panton-Valentine leukocidin c. Collagen-adhesin protein d. Microbial biofilm e. Toxic Shock Syndrome Toxin-1 (TSST-1) Prosthetic Joint Infection (PJI): Epidemiology Del Pozo JL, Patel R. N Engl J Med 2009; 361(8): 787-794. Pathogenesis of PJI . Only small number organisms needed . Such organisms adhere to implant and form biofilm in which they are protected from antibiotics and immune system . Often skin organisms inoculated at implant . Occasionally hematogenously inoculated . Occasionally locally inoculated via infected adjacent tissue Biofilm – Bacteria’s Best Friend Image used with permission of Centers for Disease Control and Prevention, Emerging Infectious Diseases Network, Atlanta, Georgia, USA Biofilm-Associated Organisms . Coagulase-negative staphylococci . Beta-hemolytic streptococci . Enterococcus species . Proteus mirabilis . Staphylococcus aureus . Viridans Streptococcus . Escherichia coli . Pseudomonas aeruginosa . Bacteroides species . Probably others Causes of PJ Failure . Aseptic loosening . Infection . Dislocation . Fracture of prosthesis or bone Patient-Related PJI Risk Factors . Previous revision arthroplasty . Previous infection in PJI at same site . Tobacco abuse . Obesity . Rheumatoid arthritis . Neoplasm . Immunosuppression . Diabetes mellitus Surgical PJI Risk Factors . Simultaneous bilateral arthroplasty . Long operative time (> 2.5 hours) . Allogeneic blood transfusion . Postoperative risk factors: . Wound complications . Atrial fibrillation . Myocardial infarction . Urinary tract infection . Prolonged hospital stay . Staphylococcus aureus bacteremia Microbiology of PJI - General Type of Organism Percentage Gram-positive cocci 65 Aerobic Gram-negative bacilli 6 Anaerobes 4 Polymicrobial 20 Culture-negative 7 Fungi 1 Del Pozo JL, Patel R. N Engl J Med 2009; 361(8): 787-793. Microbiology of PJI - Specific Pathogen Percentage Staphylococcus aureus 20-25 Coagulase-negative staphylococci 20-30 Polymicrobial 12-19 Gram-negative bacilli 6-11 Streptococci 8-10 Anaerobies including Propionibacterium 4-10 Enterococcus species 3 Other or unknown 1 Sia, Berbari, Karchmer. Infect Dis Clin N Am 2005; 19: 885-914. Criteria for Diagnosis of PJI Presence of at least ONE of the following: 1. Acute inflammation detected on histopathological examination of periprosthetic tissue 2. Sinus tract communicating with the prosthesis 3. Gross purulence in the joint space 4. Isolation of same organism from 2 or more cultures of joint aspirates OR intraoperative periprosthetic-tissue specimens (> 20 CFU), OR both Diagnostic Methods for PJI . Elevated C-Reactive Protein > 13.5 mg/L: CRP to normal 2 months after surgery whereas ESR stays high for several months . Imaging: . X-ray: low sensitivity . CT & MR: lots of scatter . Technitium scan: sensitive for failure but not specific for infection . Combined Indium-111 labeled leukocyte scan with marrow imaging with technetium-99m-labeled sulfur colloid is best test currently Diagnostic Methods for PJI . Synovial fluid studies predict infection: . Knee aspirate: > 1,700/cmm; > 65% PMN . Hip aspirate: > 4,200/cmm; > 80% PMN (These are dramatically lower than numbers for native joint infection.) Prosthetic Joint Knee Aspirate Trampuz et al. Am J Med 2004; 117: 556-562. Prosthetic Hip Aspirate - PJI Schinsky MF et al. J Bone Joint Surg Am 2008; 90: 1869-1875. Culture Diagnosis of PJI . Collection of multiple periprosthetic-tissue specimens for aerobic and anaerobic bacterial culture is imperative because of . Poor sensitivity of a single culture . Distinguish contaminants from pathogens . Swab cultures and Gram stains have poor sensitivity . Five or six cultures (not swabs) should be submitted for culture . Two or three culture-positive samples would be considered diagnostic Atkins BL et al. J Clin Microbiol 1998; 36(10): 2932-2939. Primary Surgical Treatment - PJI . Debridement with retention of prosthesis . One-stage replacement . Two-stage replacement . Arthrodesis of joint . Amputation Secondary Treatment - PJI . Protracted intravenous antibiotic therapy . Follow-up oral antibiotic therapy . Long-term suppressive oral antibiotic therapy . Prophylactic antibiotic therapy (when appropriate) . Implanted antibiotic therapy: . In spacer . In “beads” Selected References 1. Atkins BL, Athanasou N, Deeks JJ et al. Prospective evaluation of criteria for microbiological diagnosis of prosthetic-joint infection at revision arthroplasty. J Clin Microbiol 1998; 36(10): 2932-2939. 2. Del Pozo JL, Patel R. Infection associated with prosthetic joints. N Engl J Med 2009; 361(8): 787-794. 3. Johannson B, Taylor J, Clark CR et al. Treatment approaches to prosthetic joing infections: results of an Emerging Infections Network survey. Diag Microbiol Infect Dis 2010; 66: 16-23. 4. Lee J, Kang CI, Lee JH et al. Risk factors for treatment failure in patients with prosthetic joint infections. J Hosp Infect 2010; 75: 273-276. 5. Leone S, Borrè S, Monforte A et al. Consensus document on controversial issues in the diagnosis and treatment of prosthetic joint infections. Int J Infect Dis 2010; 14(S4): S67-S77. 6. Moran E, Byren I, Atkins BL. The diagnosis and management of prosthetic joint infections. J Antimicrob Chemother 2010; 65(S3): iii45-iii54. 7. Schinsky MF, Valle CJD, Sporer SM et al. Perioperative testing for joing infection in patients undergoing revision total hip arthroplasty. J Bone Jt Surg- Am 2008; 90: 1869-1875. 8. Sia IG, Berbari EF, Karchmer AW. Prosthetic joint infections. Infect Dis Clin N Am 2005; 19: 885-914. 9. Trampuz A, Hanssen AD, Osmon DR et al. Synovial fluid leukocyte count and differential for the diagnosis of prosthetic knee infection. Am J Med 2004; 117: 556-562. Post-Test Question No. 1 1. What is the most common class of micro-organisms causing prosthetic joint infections? a. Aerobic Gram-negative bacilli (e.g. Pseudomonas) b. Anaerobic Gram-negative bacilli (e.g. Bacteroides) c. Anaerobic Gram-positive bacilli (e.g. Clostridium) d. Aerobic Gram-positive cocci (e.g. Staphylococcus) e. Amaerobic Gram-positive cocci (e.g. Peptococcus) Post-Test Question No. 2 2. What is the most important pathogenic mechanism for organisms causing prosthetic joint infection? a. α - haemolysin b. Panton-Valentine leukocidin c. Collagen-adhesin protein d. Microbial biofilm e. Toxic Shock Syndrome Toxin-1 (TSST-1) .