Using an Absorbable Antibacterial Mesh to Treat Biofilm-Related Driveline Infections: An In Vitro Study

Purpose Recurrent driveline infections due to biofilm formation in the tissue tunnel are extremely challenging to manage. Efficacy of antimicrobials are greatly hindered by the presence of mature biofilms. TYRXTM Absorbable Antibacterial Mesh (TYRX) has been used as a local anti-infective prophylaxis for patients with cardiac implantable devices. The aim of this study was to assess the potential of TYRX in treating biofilm-related driveline infections using in vitro assays. Methods Reference strains and clinical isolates from patients with driveline infections were used, including Staphylococcus aureus, Staphylococcus epidermidis and Pseudomonas aeruginosa. Susceptibility testing was performed with rifampicin and minocycline (antibiotics impregnated in TYRX), their combination, and other local antibiotics, on bacteria grown as planktonic cells and biofilms in 96-well microplates. Minimum inhibitory concentration (MIC), minimum bactericidal concentration, and the minimum biofilm eradication concentration (MBEC) were determined. An interstitial biofilm assay that mimics the driveline tunnel was used to evaluate the activity of TYRX in killing biofilms on HMIII driveline smooth and velour sections. Results High concentrations (133-2600 x MIC) of local antibiotics were required to kill microplate-based biofilms. Rifampicin outperformed other antibiotics in eradicating staphylococcal biofilms, supported by the lowest MBECs (8-16 mg/L). Rifampicin and minocycline appeared to be synergistic, with a combination at MIC eradicating microplate-grown staphylococcal biofilms. A layer of TYRX in the tunnel for 24 h killed staphylococcal biofilms on smooth drivelines by 2.1-6.8 logs, and that on velour by 1.0-2.3 logs, more effective than local vancomycin at 2560 mg/L (Fig. 1). There was minimal antimicrobial activity of TYRX against P. aeruginosa biofilms. Conclusion TYRX may be useful in treating staphylococcal but not pseudomonal driveline infections.