PURPOSE: Endotracheal Tubes (ETT) contribute to the pathogenesis of ventilator associated pneumonia (VAP), which involves microbial colonization of the aerodigestive tract and aspiration of contaminated secretions. In addition to impairing natural defense mechanisms such as the cough reflex and swallowing, the endotracheal tube can become colonized with potentially pathogenic microorganisms. Microbial biofilms which provide a protected environment for pathogens may accumulate on both the inner and the outer surface of the ETT and detach spontaneously or during suctioning or bronchoscopy, contaminating the lower respiratory tract. An in vitro assessment of microbial colonization and biofilm formation on sixteen endotracheal tubes following extubation was conducted.
METHODS: The microbiological assessment compared two types of ETT: a proprietary silver-coated ETT (Agento IC, C.R. Bard Inc) and a standard, non-coated ETT. Microbial colonization and biofilm formation were assessed by culture techniques as well as by confocal laser scanning microscopy and scanning electron microscopy.
RESULTS: Analysis of several locations on the inner and outer surface of the ETT showed overall lower colonization rates on silver coated ETT than on non-coated tubes. For both sample groups, highest colonization rates were detected on the outer surface just above the cuff. Pathogenic microorganisms were detected on 3 out of 7 of non coated tubes (Pseudomonas aeruginosa, Staphylococcus aureus), but no pathogenic microorganisms were present on any of the 9 silver coated endotracheal tubes. A reduction of live microorganisms embedded in mucus particles was observed on silver coated samples compared to non coated tubes.
CONCLUSION: An overall trend toward lower colonization rates and a trend to less colonization with pathogens was observed with silver coated endotracheal tubes compared to non coated ETT.None of these differences were statistically significant, probably due to the small sample size.
CLINICAL IMPLICATIONS: The findings in this limited in vitro study are consistent with an antimicrobial effect of the silver coatings and are in agreement with previous clinical reports of reduced biofilm formation on silver coated endotracheal tubes.
DISCLOSURE: Silke Talsma, Grant monies (from industry related sources) This study was supported by CR Bard; Employee S. Talsma is an employee of CR Bard; Product/procedure/technique that is considered research and is NOT yet approved for any purpose. The microbiology study was conducted as sub-study of a randomized controlled clinical trial under an IDE.