What is the role of synovial fluid culture in the diagnosis of septic arthritis?

Updated: Sep 19, 2017
  • Author: John L Brusch, MD, FACP; Chief Editor: Michael Stuart Bronze, MD  more...
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Answer

Culture of the synovial fluid or of synovial tissue itself is the only definitive method of diagnosing septic arthritis. Culture results in patients with nongonococcal septic arthritis are almost always positive, unless the patient has received antibiotics before the joint aspiration. Cultures of the joint fluid in gonococcal infections yield positive results in only about 25% of cases. If this diagnosis is suspected, the organism can be cultured from other sites, such as the cervix, urethra, or throat. The effectiveness of standard culture techniques is much more limited in patients with prosthetic joint infection (PJI), probably because of the high rate of antibiotic preadministration prior to arthrocentesis or surgery. If the patient is clinically stable, stop the administration of antibiotics for 2 weeks prior to obtaining cultures and hold for 14 days.

A minimum of 3 and preferably 6 periprosthetic tissue samples should be obtained. Ultrasonication of removed prosthetic material increases the return of cultures, especially in patients who had recently received antibiotics. This technique also helps retrieve organisms that reside in the biofilms that coat the prosthetic material. [22]

If possible, stopping antibiotics for 4 days and holding cultures for 14 days may increase the yield. [23]

In addition, sonication of removed prosthetic material appears to increase the sensitivity of culture, especially in patients who have received antibiotics before surgery.


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