Poster Presentation Australian Society for Microbiology Annual Scientific Meeting 2017

Infection associated with Prosthetic Joint Tissue – A comparison using blood culture media against existing laboratory protocols (#229)

Nathan Lee 1 , Tobin Hillier 2 , Melanie Wildey 1 , Jacqueline Harper 2 , Keat Choong 3
  1. Pathology Queensland Central Laboratory, Royal Brisbane and Women’s Hospital, Herston, QLD, Australia
  2. Pathology Queensland, Herston, QLD, Australia
  3. Infectious Diseases, Sunshine Coast University Hospital, Birtinya, QLD, Australia

Prosthetic joint infections (PJI) are one of the major challenges presented to orthopaedic and infectious disease clinicians post arthroplasty3.  Intravenous or oral antimicrobial therapy and surgery is almost always a necessity for the management of PJIs.  To confirm infection and ensure correct antimicrobial therapy is administered to the patient, laboratory culture is of utmost importance.  Routine culture using enrichment broth and agar media reportedly has low sensitivity for chronic infection2.  Culture in blood culture media could potentially increase pathogen yield and result in earlier detection times.

The aim of this study is to trial and compare current standardized prosthetic joint tissue procedures in Microbiology against homogenized prosthetic joint tissue inoculated into blood culture media.  This study was conducted over a 7-month period and included all prosthetic joint tissues, including single and multiple joint replacements/revisions (e.g. hip, knee, shoulder) with a potential diagnosis of prosthetic joint infection.  Overall 83 patients were studied culminating in 90 episodes involving 1 to 10 specimens per episode collected from 7 different hospitals analysed by Pathology Queensland at the Central (Royal Brisbane Hospital) and Nambour Base Hospital Laboratories, Queensland, Australia.  Of the 90 episodes, 26 episodes met IDSA (Infectious Diseases Society of America) criteria2. From this cohort: 19 episodes had organisms isolated on all media types; 4 episodes had growth in enrichment broth (EBM) and blood culture media (BCM), but not on agar plates; 1 episode grew in BCM only; 1 episode grew in EBM only.  Time to detection (TTD) varied based on the method used: 1.2 days TTD for BCM; 2.8 days TTD for agar plates and EBM combined.  Results of our study demonstrated that although sensitivity overall did not improve when compared against the conventional method, TTD was significantly earlier, especially in the detection of possible multi-resistance organisms, which may facilitate more targeted antimicrobial therapy.