Investigation of biofilm formation on a charged intravenous catheter relative to that on a similar but uncharged catheter

Abstract

Guy A Richards,1,2 Adrian J Brink,3 Ross McIntosh,4 Helen C Steel,5,6 Riana Cockeran5,61Department of Critical Care, Charlotte Maxeke Johannesburg Academic Hospital, 2Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa; 3Department of Clinical Microbiology, Ampath National Laboratory Services, Milpark Hospital, Johannesburg, South Africa; 4Nano-Scale Transport Physics Laboratory, School of Physics, University of the Witwatersrand, Johannesburg, South Africa; 5Medical Research Council Unit for Inflammation and Immunity, Department of Immunology, University of Pretoria, Pretoria, South Africa; 6National Health Laboratory Service, Pretoria, South AfricaAbstract: Catheter-related blood stream infections increase morbidity, mortality, and costs. This study investigated whether Certofix® protect antimicrobial catheters carry a surface charge and whether this inhibits biofilm formation. The capacitance of the catheter surfaces was measured and, to determine if the catheters released ions, distilled water was passed through and current measured as a function of voltage. With probes touching the inner and outer surfaces, capacitance was not voltage-dependent, indicating surfaces were uncharged or carried a similar charge. When one probe penetrated the catheter wall, capacitance was weakly voltage-dependent, indicating the presence of a surface charge. Standard and charged catheters were also exposed to phosphate buffered saline as controls or 2×106 colony forming units/mL (in phosphate buffered saline) of six different microorganisms for 60 or 120 minutes. When the growth of detached bacteria was measured, biofilm formation was significantly reduced, (P<0.05), for charged catheters for all organisms.Keywords: central venous catheters, electrical charge, biofilm