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Decreased Staphylococcus aureus biofilm formation on nanomodified endotracheal tubes: a dynamic airway model

Authors Machado MC, Tarquinio KM, Webster T 

Received 12 November 2011

Accepted for publication 29 December 2011

Published 19 July 2012 Volume 2012:7 Pages 3741—3750


Review by Single anonymous peer review

Peer reviewer comments 2

Mary C Machado,1 Keiko M Tarquinio,2 Thomas J Webster3

1School of Engineering, Brown University, Providence, RI; 2Division of Pediatric Critical Care Medicine, Rhode Island Hospital, Providence, RI; 3School of Engineering and Department of Orthopedics, Brown University, Providence, RI, USA

Abstract: Ventilator-associated pneumonia (VAP) is a serious and costly clinical problem. Specifically, receiving mechanical ventilation for over 24 hours increases the risk of VAP and is associated with high morbidity, mortality, and medical costs. Cost-effective endotracheal tubes (ETTs) that are resistant to bacterial infections could help prevent this problem. The objective of this study was to determine differences in the growth of Staphylococcus aureus on nanomodified and unmodified polyvinyl chloride (PVC) ETTs under dynamic airway conditions simulating a ventilated patient. PVC ETTs were modified to have nanometer surface features by soaking them in Rhizopus arrhisus, a fungal lipase. Twenty-four-hour experiments (supported by computational models) showed that airflow conditions within the ETT influenced both the location and the concentration of bacterial growth on the ETTs, especially within areas of tube curvature. More importantly, experiments revealed a 1.5 log reduction in the total number of S. aureus on the novel nanomodified ETTs compared with the conventional ETTs after 24 hours of airflow. This dynamic study showed that lipase etching can create nanorough surface features on PVC ETTs that suppress S. aureus growth, and thus may provide clinicians with an effective and inexpensive tool to combat VAP.

Keywords: biofilm, laminar flow, ventilator-associated pneumonia, nanotechnology, endotracheal tubes, S. aureus

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