Cultures and Gm Staining of Synovial Fluid

- 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

- See synovial fluid analysis of infected knee replacement / hip replacement


Role of knee aspiration after resection of the infected total knee arthroplasty.

The Coventry Award. The value of preoperative aspiration before total knee revision.

Microbiology and management of joint and bone infections due to anaerobic bacteria.

Gram staining in the diagnosis of acute septic arthritis

The fate of acutely inflamed joints with a negative synovial fluid culture.



Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Friday, December 6, 2013 9:41 am