A rabbit model for evaluation of catheter-associated fungal biofilms

Abstract

AutOphAgic punctum 466 Virulence Volume 2 issue 5 M ost cases of catheter-related bloodstream infections (CRBSIs) involve colonization of microorganisms on catheter surfaces where they eventually become embedded in a biofilm. Fungal biofilm formation is studied using a number of techniques, involving the use of a wide variety of substrates and growth conditions. In vitro techniques involving use of confocal scanning laser/scanning electron microscopy, metabolic activity assay, dry weight measurements and antifungal susceptibility assays are increasingly used by investigators to quantify and evaluate biofilm morphology. However, there are not many in vivo models used to validate biofilm-associated infections. In this protocol, we describe clinically relevant rabbit model of C. albicans biofilm-associated catheter infection to evaluate the morphology, topography and architecture of fungal biofilms. The methods described here can be completed in a typical laboratory setting. Evaluation of the formation of fungal biofilms on catheters in vivo, their analysis using scanning electron microscopy (SEM) and quantitative catheter culture (QCC) and treatment of biofilms using antimicrobial lock therapy can be completed using the described methods in ~20-25 d. This model has utility in evaluating the efficacy of lock solutions. In addition, it is a useful approach for characterizing/comparing the formation of biofilms by wild-type and isogenic mutants including clinical isolates in vivo. This model can also be used for testing different biomaterials.

Methodologies for in vitro and in vivo evaluation of efficacy of antifungal and antibiofilm agents and surface coatings against fungal biofilms

“…Biofilms are notoriously difficult to treat and eradicate and therefore, several biofilm model systems have been developed and used to test the efficacy of antibiofilm molecules 308 309 . The first model was a rabbit model of C. albicans biofilm-associated catheter infection using a catheter-lock system to determine the efficacy of antifungal treatment 310 311 . In the same year, Andes et al developed a rat central venous catheter (CVC) model which was also used to test the efficacy of antifungals 72 193 203 312 313 .…”

Recent insights into Candida albicans biofilm resistance mechanisms

“…In the early years, major focus was on bacterial biofilms, with a first model to study C. albicans biofilm development in vitro only emerging in 1994 (Hawser and Douglas 1994 ). Since then, ample model systems for the study of fungal biofilms have been developed (Tournu and Van Dijck 2012 ) and C. albicans biofilm formation has been characterized both in vitro and in vivo by several research groups (Andes et al 2004 ; Chandra et al 2001a , 2011 ; Řičicová et al 2010 ). In general, C. albicans biofilm formation is characterized by four stages: (1) cell-wall protein-mediated adherence of yeast cells to a surface, (2) growth of the attached yeast cells into a thin layer of cells, (3) maturation of the biofilm through development of pseudohyphae and hyphae and excretion of matrix material and (4) dispersal of yeast cells from the biofilm possibly leading to colonization of distant places (Blankenship and Mitchell 2006 ; Chandra et al 2001a ; Kaneko et al 2013 ; Uppuluri et al 2010 ).…”

Candida albicans Biofilm Development and Its Genetic Control

“…We believe that the simplest approach to validate in vitro observations is to use an animal model of biofilm-based infection. There are animal models (10) for venous catheter infection (11,12), urinary catheter infection (13), and denture stomatitis infection (14). (For review, see chapter by Nett and Andes in this volume.)…”