- 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;
