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12: MICRO-PATTERNED SURFACES FOR REDUCING BACTERIAL BIOFILM FORMATION ON ENDOTRACHEAL TUBES A NOVEL APPROACH TO DECREASING THE INCIDENCE OF VENTILATOR-ASSOCIATED PNEUMONIA

May, Rhea; Hoffman, Matthew; Reddy, Shravanthi

doi: 10.1097/01.ccm.0000424268.20384.7b
Oral Abstract Session: ABSTRACT Only

Introduction: Ventilator-associated pneumonia (VAP) is a leading HAI in ICUs 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. A novel bio-inspired micro-topography may provide an alternative strategy for VAP prevention as it has been shown to reduce microbial attachment, migration and biofilm formation of several pathogens without the use of antimicrobial agents.

Hypothesis: Micro-topography will reduce biofilm formation of VAP-associated pathogens in a medium mimicking the tracheal environment.

Methods: To obtain mature Pseudomonas aeruginosa biofilms, patterned and un-patterned silicone samples (n=3) were immersed in arginine minimal medium with 2g/L porcine mucin and 400 mg/L oxacillin for 24hrs at 37°C. Four day Staphylococcus aureus biofilms developed in TSB media as described above. Experiments were completed in triplicate. Air-liquid interface P. aeruginosa biofilms grew on tilted samples (n=3) in mucin and oxacillin supplemented TSB. All samples were rinsed, fixed, dehydrated, and stained with propidium iodide. Image stacks were obtained in three pre-selected sites per sample by confocal laser scanning microscopy. Volumetric analysis was achieved by totaling biofilm area coverage in each z-stack and significance was assessed by student t-test or ANOVA models.

Results: The micro-pattern reduced P. aeruginosa biofilm formation in a mucin-rich environment by an average of 58% (p<0.01) when compared to control surfaces. Four day S. aureus biofilms were reduced by an average of 67% (p=0.01). In an alternative model that simulates the air-liquid interface present on an ETT, P. aeruginosa biofilms were reduced by 44% (p<0.01).

Conclusions: The micro-pattern surface modification inhibits the formation of P. aeruginosa biofilms in two models using a medium that mimics the tracheal environment. This pattern also reduces S. aureus biofilms, thereby demonstrating performance against two key VAP-associated species. These data suggest that the micro-pattern may prevent VAP without the use of antimicrobials if applied to the surface of an ETT.

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© 2012 by the Society of Critical Care Medicine and Lippincott Williams & Wilkins