Outcome of Treatment of Patients with Culture Negative Periprosthetic Infection

1. Outcome of Treatment of Patients with Culture Negative Periprosthetic Infection Rothman Institute Thomas Jefferson University Hospital Philadelphia, PA Benjamin Bender MD Ashok Gowda BS Khalid Azzam MD Elie Ghanem MD James Purtill MD Javad Parvizi MD, FRCS

2. Periprosthetic joint infection (PJI) • 1.5%–2.5% after primary hip or knee arthroplasty • Marked morbidity and mortality • Challenging

3. Periprosthetic joint infection (PJI) • Effective delivery of antibiotics • Based on the type and antibiotic sensitivity of the infecting organism

4. This study reports • The high false negative rate of microbiological studies And • Compares the outcome of treatment for PJI when the organism was identified versus culture negative cases.

5. Methods/Materials • Patients with PJI between 1999 to 2006 • Electronic microbiological database (1999) • Detailed review of medical records

6. Methods/Materials • 384 patients (189 women/195 men) • 219 knee / 165 hip • Mean age 66.6 years (17-94)

7. Materials and Methods Criteria for diagnosis of infection: • Positive preoperative aspiration Cultures, Gram stains • Positive intraoperative Cultures, Gram stains and/or • the presence of an abscess or sinus tract communicating with the joint space • Clinical suspicion • Abnormal serology

8. Procedure performed

9. Results • Gram positive cocci cause 90% of PJI, and gram negative organisms account for most of the remaining infections. • Gram positive in 269 cases (89.7%) • Gram negative in 30 cases (10%) • Fungus in 1 case (0.3%)

10. Results-Intraoperative cultures Diagnosis of PJI was based on • Positive Intraoperative cultures in 309 patients (80%) • 20% False Negative

11. Results-Intraoperative GRAM STAIN • 340 patients-89%-had Gram stain performed • 71 patients had Positive result-( 21%) • 269 patients – (79%) False Negative

12. Results- Gram Stain (Aspiration) 276 patients -72% had pre-operative Aspiration • 93 patients (34 %) had positive GRAM stains • 217 patients (66%) had false negative results

13. Results- Culture(Aspiration) 276 patients -72% had pre-operative Aspiration • 217 patients (79%) had Positive CULTURE results • 59 patients (21%) had false negative results

14. Results-Overall

15. Results • Cultures were negative overall in 53 cases (14%) that satisfied defined criteria for diagnosis of PJI • Infecting Organism was identified in 331 cases(86%)

17. Results-Outcome • SF-36 • WOMAC • HSS/KSS Better for culture positive • Success for eradication of infection • Better for culture positive • 85% vs 75% for false negative

18. Conclusions • The inability to isolate an infecting organism causing periprosthetic joint infection appears to compromise the outcome of surgical treatment

19. Conclusions • The reason for the inability to isolate the infecting organism may be multi-factorial • Important of which relates to the use of antibiotics at the time of or close to the date of aspiration or tissue culture.

20. Conclusion • Every effort should be made to isolate the infecting organism whenever possible This includes • Cessation of antibiotics for sufficient time prior to aspiration, repeat aspiration • Utilization of molecular techniques for isolation of the organism.

21. THANK YOU PHILADELPHIA, PA 19107, USA