• Clarke, Professor Stuart
• Thurner, Philipp J.
• Stoodley, Paul
• Bull, Daniel
• Faust, Saul
• Calton, Elizabeth
• Johnston, David
• Jones, Gareth L.
• Howlin, Robert
• Niehaus, Wilmari
• Mavrogordato, Mark

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 optimises X-ray micro computed tomography (X-ray µCT) for the quantification and determination of distribution and heterogeneity of biofilms in in vitro central venous catheter (CVC) model systems.<br/><br/>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 optimise these methods. Catheter material and biofilm were segmented using a semi-automated MATLAB script and quantified using the Avizo Fire software package.<br/><br/>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 optimised 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.<br/><br/>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.

Topics

• compound
• silver
• scanning electron microscopy
• tomography
• gold
• Energy-dispersive X-ray spectroscopy