Infectious profiles in civilian gunshot associated long bone fractures

Abstract

Purpose: There is a paucity of literature on infections in civilian gunshot associated with long bone fractures with the reported rates ranging from 0-15.7%.This study aimed to investigate the rates of infection associated with long bone fractures caused by civilian gunshots. The specific objectives were to determine if certain extremities were at a higher risk for infection and to identify the types of bacteria present in these infections by analyzing culture isolates.

Methods: We conducted a retrospective review of consecutive patients aged 18-64 who sustained gunshot-associated long bone fractures at an urban Level I trauma centre from 2010 to 2017. Patient selection was based done through a institutional trauma centre database using international classification of diseases (ICD) 9 and 10 codes. We included patients who underwent surgical treatment, specifically fracture fixation, at our institution and excluded patients with fractures involving the pelvis, spine, foot, and hand. A total of 384 gunshot-associated long bone fractures in 347 patients were identified for analysis. Relevant patient-, injury-, and treatment-related variables were extracted from clinical records and radiographic reviews. Outcomes of interest included bony union, repeat operative procedures, and the development of deep infection.

Results: 347 patients with 384 long bone fractures were included. 32 fractures in 32 patients developed an infection for an incidence of 9.3% of patients and 8.3% of fractures. Gram-positive bacteria were present in 23/32 (72.0%) culture isolates, gram-negative bacteria in 10/32 (31.3%) culture isolates, and six infections were polymicrobial. Staphylococcus 16/32 (50.0%) and Enterobacter 6/32 (18.8%) species were the most common isolates. Of the Staphylococcus species, 5/16 (31.3%) were MRSA. Lower extremity fractures had a greater risk for infection compared to the upper extremity (11.7% vs 3.7% p < 0.01) and fractures that developed an infection had a larger average zone of comminution (63.9 mm vs 48.5 mm p < 0.05).

Conclusion: This study investigated the rates of infection associated with long bone fractures caused by civilian gunshots. The overall infection rate observed in our series aligns with existing literature. Gram-positive bacteria were the predominant isolates, with a notable incidence of MRSA in our patient population, highlighting the need for considering empiric coverage. Additionally, gram-negative organisms were found in a significant proportion of infections, and a notable percentage of infections were polymicrobial. Our findings emphasize the importance of carefully assessing highly comminuted lower extremity fractures and implementing appropriate antibiotic coverage and operative debridement for patients with gunshot-related long bone fractures. While current prophylaxis algorithms for open fractures lack specific inclusion of gunshot wounds, we propose incorporating these injuries to reduce the incidence of infections associated with such fractures.

Keywords: Antibiotics; Femur; GSW; Infection; Micro; Tibia.