title: Development of X-ray micro-focus computed tomography to image and quantify biofilms in central venous catheter models in vitro.
abstract: Bacterial infections of central venous catheters (CVCs) cause much morbidity and mortality, and are usually diagnosed by concordant culture of blood and catheter tip. However, studies suggest that culture often fails to detect biofilm bacteria. This study optimizes X-ray micro-focus computed tomography (X-ray µCT) for the quantification and determination of distribution and heterogeneity of biofilms in in vitro CVC model systems.Bacterial culture and scanning electron microscopy (SEM) were used to detect Staphylococcus epidermidis ATCC 35984 biofilms grown on catheters in vitro in both flow and static biofilm models. Alongside this, X-ray µCT techniques were developed in order to detect biofilms inside CVCs. Various contrast agent stains were evaluated using energy-dispersive X-ray spectroscopy (EDS) to further optimize these methods. Catheter material and biofilm were segmented using a semi-automated matlab script and quantified using the Avizo Fire software package. X-ray µCT was capable of distinguishing between the degree of biofilm formation across different segments of a CVC flow model. EDS screening of single- and dual-compound contrast stains identified 10 nm gold and silver nitrate as the optimum contrast agent for X-ray µCT. This optimized method was then demonstrated to be capable of quantifying biofilms in an in vitro static biofilm formation model, with a strong correlation between biofilm detection via SEM and culture. X-ray µCT has good potential as a direct, non-invasive, non-destructive technology to image biofilms in CVCs, as well as other in vivo medical components in which biofilms accumulate in concealed areas.
authors.affiliation: National Centre for Advanced Tribology at Southampton (nCATS), Faculty of Engineering and the Environment (FEE), University of Southampton, UK.|Southampton NIHR Wellcome Trust Clinical Research Facility, University Hospital Southampton NHS Foundation Trust, Southampton, UK.|Southampton NIHR Biomedical Research Centre and NIHR Respiratory Biomedical Research Unit, University of Southampton and University Hospital Southampton NHS Foundation Trust, Southampton, UK.|Faculty of Medicine, University of Southampton and University Hospital Southampton NHS Foundation Trust, Southampton, UK.
authors.forename: Wilmari L
authors.initials: WL
authors.lastname: Niehaus
authors.affiliation: Southampton NIHR Biomedical Research Centre and NIHR Respiratory Biomedical Research Unit, University of Southampton and University Hospital Southampton NHS Foundation Trust, Southampton, UK.|Centre for Biological Sciences, Faculty of Natural and Environmental Sciences and Institute for Life Sciences, University of Southampton, Southampton, UK.
authors.forename: Robert P
authors.initials: RP
authors.lastname: Howlin
authors.affiliation: Faculty of Medicine, University of Southampton and University Hospital Southampton NHS Foundation Trust, Southampton, UK.|Biomedical Imaging Unit, University Hospital Southampton NHS Foundation Trust, Southampton, UK.
authors.forename: David A
authors.initials: DA
authors.lastname: Johnston
authors.affiliation: Engineering Materials Research Group, FEE, University of Southampton, UK.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Bull
authors.affiliation: Centre for Hybrid Biodevices, Electronics and Computer Science, University of Southampton, UK.
authors.forename: Gareth L
authors.initials: GL
authors.lastname: Jones
authors.affiliation: Southampton NIHR Wellcome Trust Clinical Research Facility, University Hospital Southampton NHS Foundation Trust, Southampton, UK.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Calton
authors.affiliation: µ-VIS X-ray Imaging Centre, FEE, University of Southampton, Southampton, UK.
authors.forename: Mark N
authors.initials: MN
authors.lastname: Mavrogordato
authors.affiliation: Faculty of Medicine, University of Southampton and University Hospital Southampton NHS Foundation Trust, Southampton, UK.|Southampton NIHR Biomedical Research Centre and NIHR Respiratory Biomedical Research Unit, University of Southampton and University Hospital Southampton NHS Foundation Trust, Southampton, UK.
authors.forename: Stuart C
authors.initials: SC
authors.lastname: Clarke
authors.affiliation: Bioengineering Science Research Group, FEE, University of Southampton, UK.|Institute of Lightweight Design and Structural Biomechanics, TU Wien, Vienna, Austria.
authors.forename: Philipp J
authors.initials: PJ
authors.lastname: Thurner
authors.affiliation: Faculty of Medicine, University of Southampton and University Hospital Southampton NHS Foundation Trust, Southampton, UK.|Southampton NIHR Biomedical Research Centre and NIHR Respiratory Biomedical Research Unit, University of Southampton and University Hospital Southampton NHS Foundation Trust, Southampton, UK.|Southampton NIHR Wellcome Trust Clinical Research Facility, University Hospital Southampton NHS Foundation Trust, Southampton, UK.
authors.forename: Saul N
authors.initials: SN
authors.lastname: Faust
authors.affiliation: National Centre for Advanced Tribology at Southampton (nCATS), Faculty of Engineering and the Environment (FEE), University of Southampton, UK.|Center for Microbial Interface Biology (CMIB), Departments of Microbial Infection and Immunity, and Orthopaedics, The Ohio State University, Columbus, OH, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Stoodley
mesh_terms: D018441:Biofilms; D055499:Catheter-Related Infections / Q000382:microbiology*; D062905:Central Venous Catheters / Q000382:microbiology*; D006801:Humans; D013203:Staphylococcal Infections / Q000000981:diagnostic imaging / Q000382:microbiology*; D013212:Staphylococcus epidermidis / Q000502:physiology* / Q000648:ultrastructure; D014054:Tomography