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Systemic Inflammatory Markers and Joint Aspirate Cell-Count are Unable to Differentiate Between Bacterial or Fungal Periprosthetic Infection.

Authors: Bracken CD, Berbari EF, Hanssen AD, Mabry TM, Osmon DR, Sierra RJ. Mayo Clinic, Rochester, MN

Title: Systemic Inflammatory Markers and Joint Aspirate Cell-Count are Unable to Differentiate Between Bacterial or Fungal Periprosthetic Infection.

Background: Fungal periprosthetic joint infection (F-PJI) is a rare entity. The characteristics of systemic inflammatory markers and joint aspirate cell count analysis obtained in patients with F-PJIs have not been fully assessed. The ability to diagnose involvement of F-PJI pre-operatively may optimize the surgical and medical management of these patients.

Hypothesis/Purpose: Are pre-operative joint fluid cell counts and systemic inflammatory markers different between patients with F-PJI and bacterial PJI?

Methods: The medical records of 44 patients with fungal periprosthetic joint infections from 1/1/2002 to 12/31/2011 were reviewed. 32 were purely fungal and 12 were mixed (bacterial/fungal) infections. Pre-operative joint aspiration fluid analyses, peripheral white count, ESR, and CRP values were documented in 89% of cases. 16 (36%) cases had pre-operative synovial fluid aspirations performed. Receiver-Operator curves (ROC) were calculated to determine the predictive value of these inflammatory markers. Values were compared to 59 culture-positive confirmed bacterial infection aspirates treated by one surgeon at the same institution over the same time period.

Results: The mean ESR values for F-PJI and bacterial PJI cases were 39.64 mm/h and 41.10 mm/h, respectively. The mean CRP values for F-PJI and bacterial PJI were 41.95 mg/L and 65.42 mg/L, respectively. The mean total nucleated cells for F-PJI and bacterial PJI were 11,928.4 with 81% Neutrophils and 36,901 with 73% Neutrophils, respectively. The sensitivities, specificities, negative predictive values, and positive predictive values for all tests were comparable in all groups.

Discussion: In this study, fluid analyses and preoperative systemic inflammatory markers were unable to differentiate between fungal, mixed, or bacterial PJIs. When there is a clinical suspicion, fungal and bacterial periprosthetic tissue cultures should be obtained in the setting of multiply failed THA or TKA infection.

Conclusion: Early detection and treatment is needed and the systemic inflammatory markers and cell count analyses from aspirations do not discriminate whether an infection may be of fungal origin.

Musculoskeletal Infecton Society
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