- Discussion:
- Cx & Gram's staining are obligatory when infection is suspected.
- Definitive diagnostic test is either the demonstration of bacteria by Gram's stain, usually best seen on a concentrated sediment of
centrifuged
synovial fluid, or the recovery of bacteria from the synovial-fluid culture;
- Gram's stains are positive in approx 75 % of pts w/
staphylococcal infections & 50% of those w/
gram-neg bacilli, but in < 25 % of pts w/
GC;
- Synovial-fluid culture is positive in almost all pts w/ nongonococcal
bacterial arthritis, unless they have recently been taking ATBs;
- Aerobic and anaerobic cultures should be routinely grown whenever joint is aspirated;
- fluid should be promptly transported to microbiology laboratory;
-
Gm-positive bacteria can be seen on well-prepared slide of cx- positive fluids approx 80 % of time;
-
Gram Positive Bacilli
-
Gram Positive Cocci
-
Gm-negative bacteria are seen less frequently, &
N. gonorrhoeae rarely seen;
-
Gram Negative Bacilli
-
Gram Neg Cocci
-
Neiserria Gonnorhea:
- unfortunately, GC is recovered in < 50% of purulent joints in pts w/ suspected disseminated GC infection;
- although this may be related to stringent growth requirements of GC, there is evidence that viable organisms may not be prerequisite for
continued synovitis in disseminated GC;
- Special stains & Cx for mycobacteria & fungi are sometimes needed;
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Role of knee aspiration after resection of the infected total knee arthroplasty.
The Coventry Award. The value of preoperative aspiration before total knee revision.
