Is it acceptable to discontinue vancomycin (vancomycin) and ceftriaxone (ceftriaxone) in a patient with knee pain, swelling, and aspirated synovial fluid showing crystals and a total nucleated cell count of 34,000, pending culture results?

From the Guidelines

Discontinuing vancomycin and ceftriaxone is acceptable in this patient with knee pain, swelling, and aspirated synovial fluid showing crystals and a total nucleated cell count of 34,000, pending culture results, as the presentation is more consistent with crystal-induced arthritis rather than septic arthritis. The presence of crystals on synovial fluid analysis, as identified in the study by 1, along with a total nucleated cell count of 34,000, strongly suggests gout or pseudogout as the primary diagnosis. Key points to consider include:

• The total nucleated cell count of 34,000, although elevated, is within a range commonly seen with crystal arthropathies, as noted in the study by 1.
• Bacterial joint infections typically present with synovial fluid cell counts above 50,000, though there can be overlap, highlighting the importance of considering crystal identification as a diagnostic criterion, as discussed in 1.
• The definitive factor is the presence of crystals, which explains the inflammatory response, as identified in the study by 1.
• It is crucial to continue monitoring the synovial fluid cultures until final results are available, typically within 48-72 hours, and to be prepared to restart antibiotics if there is any clinical deterioration or if cultures return positive, as emphasized in 1.
• Treatment should focus on managing the crystal-induced inflammation with appropriate anti-inflammatory medications such as colchicine, NSAIDs, or corticosteroids, depending on the patient's comorbidities and the specific crystal type identified, as suggested by the evidence presented in 1.

From the Research

Discontinuing Vancomycin and Ceftriaxone in a Patient with Knee Pain and Aspirated Synovial Fluid Showing Crystals

• The patient's total nucleated cell count of 34,000 is below the commonly used threshold of 50,000/mm3 to diagnose septic arthritis 2.
• However, the presence of crystals in the synovial fluid does not rule out septic arthritis, as the two conditions can coexist 3, 4, 5.
• A study found that a synovial cell count cutoff of 85,000/mm3 may be more appropriate to diagnose concomitant septic arthritis and crystalline arthropathy 6.
• Given the patient's cell count is below this threshold, it may be reasonable to consider discontinuing vancomycin and ceftriaxone, but this decision should be made with caution and careful consideration of the patient's overall clinical presentation.
• It is essential to await culture results to confirm the presence or absence of septic arthritis, as the diagnosis cannot be made solely on the basis of synovial fluid analysis 2, 3.

Considerations for Discontinuing Antibiotics

• The patient's clinical presentation, including knee pain, swelling, and aspirated synovial fluid showing crystals, suggests a possible diagnosis of crystal-induced arthritis.
• However, the possibility of coexisting septic arthritis cannot be excluded without a positive culture result or a synovial cell count above the threshold of 85,000/mm3 6, 5.
• Discontinuing vancomycin and ceftriaxone without confirmation of the absence of septic arthritis may put the patient at risk of untreated infection 2, 3.