2008 Abstract : 9

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Authors: Bender B, Gowda A, Azzam K, Ghanem E, Purtill J., Parvizi J

Title: Diagnosing Periprosthetic Infection: High False Rate Results of Microbiological Studies

Institution: Rothman Institute, Philadelphia, PA

Purpose: This study compares the outcome of treatment for PJI when the organism was identified versus culture negative cases.

Methods: All patients with proven PJI who underwent surgical treatment at our institution between1999 and 2006 were included. There were 384 patients with a mean age of 66.6 years (range, 17-94 years). Preoperative joint aspiration was performed in 254 patients (66%), intraoperatively gram stain and culture was done on all cases.

Results: Positive cultures were identified in 331 patients (86%) intraoperatively, and in 143 patients (71 %) on preoperative aspiration. Cultures were negative in 53 cases (14%) that satisfied defined criteria for diagnosis of PPI. The outcome of surgical treatment was successful in 85% of culture positive cases versus 75 % of culture negative cases.

Discussion and Conclusion: The inability to isolate an infecting organism causing periprosthetic joint infection appears to compromise the outcome of surgical treatment. The reason for the inability to isolate the infecting organism maybe related to a number of factors including the use of antibiotics at the time of or close to the date of aspiration or tissue culture. There appears to be a dire need for design of diagnostic methods that will enable clinicians to isolate infecting organisms and deliver appropriate antibacterial treatment.