Providing an Evidence Base for Tissue Sampling and Culture Interpretation in Suspected Fracture-Related Infection.

Area of Science:

• Orthopedics
• Infectious Diseases
• Medical Microbiology

Background:

• The current definition of fracture-related infection (FRI) relies on identifying microorganisms in surgical specimens.
• The optimal number of specimens and diagnostic thresholds for microbiological testing in suspected FRI cases remain unvalidated.

Purpose of the Study:

• To validate the accuracy of different numbers of deep-tissue specimens and diagnostic cut-offs for microbiological testing in patients with suspected FRI.
• To assess the sensitivity and specificity of various specimen numbers for FRI diagnosis.

Main Methods:

• A retrospective analysis of 513 surgical procedures in 385 patients with suspected FRI.
• Resampling techniques were used to model the sensitivity and specificity of diagnostic cut-offs for the number of specimens yielding microorganisms.
• FRI was defined by non-microbiological confirmatory criteria.

Main Results:

• A cut-off of at least 2 of 5 specimens with indistinguishable microorganisms showed 68% sensitivity and 87% specificity for FRI diagnosis.
• Using 2 out of 3 specimens yielded 60% sensitivity and 92% specificity.
• Submitting only 3 specimens risked missing clinically relevant microorganisms in over 10% of cases.

Conclusions:

• The study supports the current microbiological criteria for diagnosing FRI.
• Analyzing a minimum of 5 deep-tissue specimens is recommended for improved diagnostic accuracy in suspected FRI cases.