Rhea M. May PhD, Matthew G. Hoffman BA, and Shravanthi T. Reddy PhD Sharklet Technologies, Inc., Aurora, Colorado, USA

Ventilator-associated pneumonia (VAP) remains a leading HAI in intensive care units despite improved patient care practices and advancements in endotracheal tube (ETT) designs. The ETT provides a conduit for bacterial access to the lower respiratory tract and a substratum for biofilm formation, both of which lead to VAP. Antimicrobial agents coated onto the ETT have been the predominant strategy for VAP prevention. A novel micro-topography (Figure 1) may provide an alternative strategy to prevent VAP as it has been shown to reduce microbial attachment, migration and biofilm formation of several pathogens without the use of antimicrobial agents (Figure 1). Pseudomonas aeruginosa is a particularly devastating lung pathogen with its natural resistance to antimicrobials, infamous ability to form persistent biofilms, and high attributable mortality of VAP patients. In order to evaluate the feasibility of this technology’s performance in the tracheal environment, P. aeruginosa biofilms were grown on micro-patterned and un-patterned surfaces in a mucin-modified media mimicking mucosal secretions.

Background

Patterned and un-patterned (control) silicone samples were immersed statically in arginine minimal medium containing ~107 CFU/mL P. aeruginosa (ATCC9027), 2mg/mL porcine mucin and 400µg/mL oxacillin for 24 hours at 37°C to obtain mature biofilms. The samples were rinsed with sterile water to remove planktonic cells, fixed with glutaraldehyde, dehydrated, and stained with propidium iodide. Confocal scanning laser microscopy was used to obtain image stacks of the biofilm in three predetermined locations on each sample, and a semi-volumetric analysis was conducted by totaling the biofilm area coverage in each stack image using ImageJ. This experiment was replicated three times.

Methods

Figure 1. Representative Scanning electron micrographs of an un-patterned (left) and Sharklet micro-patterned (right) surface after a 14 day Staphylococcus aureus biofilm assay. Images from Chung 2007 Biointerphases 2(2):89-94

Results

Conclusions The physical micro-pattern surface modification inhibits the formation of P. aeruginosa biofilms in a media that mimics the tracheal environment. Introduction of this micro-pattern on an ETT surface may be useful in preventing VAP.

Micro-Patterned Surfaces for Reducing Pseudomonas aeruginosa Biofilm Formation on Endotracheal Tubes: A Novel Approach to Decreasing the Incidence of Ventilator-

Associated Pneumonia

Figure 2. The Sharklet micro-pattern reduces P. aeruginosa biofilm formation in a mucin-rich environment by an average of 58% (p=0.009), as averaged over results from three separate experiments. A representative image per surface type from each experiment was obtained by compiling the stack of imaged taken through the biofilm.

Acknowledgements •Sharklet would like to thank Melinda Sogo for helping to carry out these studies.

•This work was financially supported by Award Number 1R43HL110444-01 from the National Institutes of Heart Lung and Blood

For inquiries/questions, please e-mail sreddy@sharklet.com

The micro-pattern reduced P. aeruginosa biofilm in a mucin-rich environment by an average of 58% (p<0.01) over three experiments when compared to the control surfaces (Figure 2).

The Sharklet micro-pattern reduces Pseudomonas aeruginosa biofilm formation in a mucin-rich environment

Experiment 1 Experiment 2 Experiment 3

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