BBOT: Bacterial Burden in Ortho Trauma Procedures

Overview

The purpose of this research project is to improve understanding of the potential role of highly sensitive bacterial tests in diagnosing infected non-healing fractures compared to the current standard of care, microbiologic culture (growing bacteria from tissue specimens in the laboratory). In order to understand the validity of the highly sensitive tests, parameters of the test in different groups of patients must be established. This study is examining how two highly sensitive tests compare to each other and to the standard of care (microbiologic culture) in three groups of patients. Group 1 is clean broken bone surgery undergoing plate and screw fixation, intramedullary nailing fixation where the fracture site is accessible, or staged treatment of a broken bones initially treated by joint spanning external fixation device. Group 2 will include patients having a plate and screws removed without clinical evidence of infection. Group 3 will be patients undergoing an initial procedure for fracture nonunion.

Infected, broken bones that do not heal are a difficult clinical problem that significantly affect patient quality of life. Current methodology for detecting bacteria (growth in laboratory cultures) is inadequate to detect infections caused by bacteria existing in a biofilm, which is the layer of "slime" found in the presence of foreign bodies (eg, implanted metal devices to fix broken bones). Advances in molecular biology have allowed development of highly sensitive tests to detect bacteria in the biofilm state. However, the limited prior research has not included control groups or compared the performance of different highly sensitive tests. To address these limitations and further define the role of highly sensitive bacterial tests in clinical practice, the investigators hypothesize that there will be increasing bacterial burden when comparing clean broken bone surgery (1st surgery) to implanted metal device removal (2nd surgery, bone healed) to index nonunion surgery (subsequent surgery, bone not healed) as measured by percentage of cases being positive for bacteria using highly sensitive bacterial tests. Further, the highly sensitive bacterial tests (Illumina MiSeq system and Ibis T5000 biosensor) will have similar ability to quantify the number of bacteria and differentiate bacterial species. Eligible patients will consist of three groups. Group 1 is clean broken bone surgery undergoing plate and screw fixation, intramedullary nailing fixation where the fracture site is accessible, or staged treatment of a broken bones initially treated by joint spanning external fixation device. Group 2 will include patients having a plate and screws removed without clinical evidence of infection. Group 3 will be patients undergoing an initial procedure for fracture nonunion. Tissue obtained at the time of surgery will be sent to the research laboratory for culture and performance of the two highly sensitive tests. The tissue samples taken will be tissue normally removed and discarded in the course of these particular procedures. The rates of positivity for culture and the highly sensitive tests will be compared amongst the three groups. Investigators will also compare bacterial count and the distribution of bacterial species found using the two highly sensitive tests. These data will then undergo statistical analysis against clinical data gathered from review of the patients' charts. The overall project goal is to establish the clinical relevance of highly sensitive bacterial tests in diagnosing infected nonunions. The ability to more accurately identify patients with infection may lead to a change in clinical decision making with respect to surgical procedure or antibiotic treatment. This project will develop an improved understanding of the potential role of highly sensitive bacterial tests in diagnosing infected nonunions compared to the current standard of care, which is growing bacteria in the laboratory under artificial conditions.