The Bioburden Associated with Severe Open Tibial Fracture Wounds at the Time of Definitive Closure or Coverage: The BIOBURDEN Study

Background: Infection is common following high-energy open tibial fractures. Understanding the wound bioburden may be critical to infection risk reduction strategies. This study was designed to identify the bioburden profile of high-energy open tibial fractures at the time of definitive wound closure or coverage and determine the relationship to subsequent deep infection.

Methods: This multicenter prospective study enrolled 646 patients with high-energy open tibial fractures requiring a second debridement surgery and delayed wound closure or coverage. Wound samples were obtained at the time of definitive closure or coverage and were cultured in a central laboratory. Cultures were also subsequently obtained from patients who underwent a fracture-site reoperation.

Results: Two hundred and six (32%) of the wounds had a positive culture at the time of closure or coverage. A single genus was identified in 154 (75%) of these positive cultures and multiple genera, in 52 (25%). Gram-positive cocci (GPCs) were identified in 98 (47%) of the positive cultures. Staphylococci were identified in 64 (31%) of the cultures, and 53 (83%) of these were coagulase-negative (CONS). Enterococci were identified in 26 (13%) of the cultures. Gram-negative rods (GNRs) were identified in 100 (49%) of the cultures; the most frequent GNR genera identified were Enterobacter (39, 19%) and Pseudomonas (21, 10%). Positive cultures were subsequently obtained from 154 (50%) of 310 revision surgeries. A single genus was identified in 85 (55%) of the 154 and multiple genera, in 69. GPCs were identified in 134 (87%) of the 154 positive cultures, staphylococci were identified in 94 (61%), and GNRs were identified in 100 (65%).

Conclusions: The bioburden in high-energy open tibial fractures at delayed closure or coverage was often characterized by pathogens of multiple genera and of genera that are nonresponsive to typically employed antibiotic prophylaxis. Awareness of the final wound bioburden might inform strategies to lower the infection rate.

Level of evidence: Prognostic Level II . See Instructions for Authors for a complete description of levels of evidence.