Clinical use
Investigation of orthopaedic tissue and fluid samples for bacterial and fungal infection.
Background
Joint replacement (arthroplasty) has become a common procedure. It is done most commonly for osteoarthritis and inflammatory arthopathies such as rheumatoid arthritis. For hip fractures, a hemiarthroplasty is one of the surgical treatment options. Hip and knee replacements are more common than replacements of shoulder, elbow, ankle and interphalangeal joints. Bilateral replacements for osteoarthritis are common in inflammatory arthritis. Revision surgery is done for the joint failure (usually loosening or recurrent dislocation) and the majority are ‘aseptic’. Around 15% of revisions are due to ‘septic’ loosening.
Organisms may be introduced into the joint during primary implantation surgery, via a haematogenous (bloodstream) route or from post-operative contamination of the wound. These may cause acute or chronic infections. Fewer organisms are required to establish infection when there is a foreign body in situ than otherwise.
Patient preparation
Obtain the tissue or fluid sample under sterile conditions.
Specimen requirements
White top sterile universal for both biopsy and aspirates.
Samples provided in formalin will not be tested by Microbiology.
Minimum volume
1ml for aspirates
Limitations and restrictions
Send to Microbiology without delay. For optimum results, samples of tissue should reach Microbiology within 2 hours of collection. Larger pieces of tissue may maintain viability of organisms longer. If delayed transport refrigerate sample. Delays over 48 hours are undesirable.
Where possible, obtain sample prior to administration of antibiotics.
Turnaround time
8 days
Analysing laboratory
Microbiology Lab, James Cook University Hospital, Marton Road, TS4 3BW
Additional information
Additional tests for PCR or Mycobacteria investigation may be requested. Please include these on the request form and contact the laboratory for further information.
If an urgent gram stain is required, please contact the laboratory prior to sending the sample so this can be performed on receipt.