Gram Stain
Moderate strength evidence supports that the practitioner avoid the use of intraoperative gram stain to rule out periprosthetic joint infection.


Three moderate (Zywiel et al. 2011, Banit et al. 2002, Spangehl et al. 1999) and one low strength (Parvizi et al. 2006) study evaluated the use of Gram stain to rule out periprosthetic joint infection. Although these studies found a positive gram stain to be a strong rule-in test, all had negative likelihood ratios over 0.5, indicating a negative Gram stain is not a strong indicator of absence of periprosthetic joint infection whether performed on synovial fluid, tissue, or sonicate fluid. One moderate strength study found sonicate fluid Gram stain may have value to rule in PJI but still showed low sensitivity reflecting poor performance in ruling out PJI (Trampuz et al. 2007).

There are no known associated risks or harms with this recommendation.

Based on current evidence, Gram stain does not seem to have utility in ruling out periprosthetic joint infection.