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

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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.