CHARACTERIZATION OF INFECTED, EXPLANTED VENTRICULAR ASSIST DEVICE DRIVELINES: THE ROLE OF BIOFILMS AND MICRO-GAPS IN THE DRIVELINE TUNNEL

ABSTRACT BACKGROUND Driveline infections remain a major complication of ventricular assist device (VAD) implantation. This study aimed to characterize in vivo microbial biofilms associated with driveline infections and host tissue integration of implanted drivelines. METHODS Nine infected and thirteen uninfected drivelines were obtained from VAD patients undergoing heart transplantation in Australia between 2016 to 2018. Each driveline was sectioned into 11 pieces of 1.5 cm in length and each section was examined by scanning electron microscopy (SEM) and viable counts for microbial biofilms. Microorganisms were cultured and identified. Host tissue integration of clinical drivelines was assessed with micro-computed-tomography and SEM. An in vitro interstitial biofilm assay was used to simulate biofilm migration in the driveline tunnel and time-lapse microscopy was performed. RESULTS Of the 9 explanted, infected drivelines, all had organisms isolated from varying depths along the velour section of the drivelines, and all were consistent with the swab culture results of the clinically infected exit site. SEM and micro-computed-tomography suggested insufficient tissue integration throughout the driveline velour, with micro-gaps observed. Clinical biofilms presented as microcolonies within the driveline tunnel, with human tissue as the substratum, and were resistant to antimicrobial treatment. Biofilm migration mediated by a dispersal-seeding mechanism was observed. CONCLUSIONS This study of explanted infected drivelines showed extensive antimicrobial-resistant biofilms along the velour, associated with micro-gaps between the driveline and the surrounding tissue. These data support enhancement of tissue integration into the velour as a potential preventative strategy against driveline infections, by preventing biofilm migration that may use micro-gaps as mediators.