ABSTRACT
OBJECTIVE: To elucidate the mechanism of action of the silver-coated endotracheal tube in models of the early pathogenesis of ventilator-associated pneumonia. DESIGN: Open-labeled, prospective, controlled, sequentially conducted, preclinical studies, and in vitro assessment of tubes from patients. SETTING: Microbiology laboratory of a device manufacturer, animal research facility of a university, and a tertiary medical center. INTERVENTIONS: Endotracheal tubes were similar except for the silver coating. In the 21-day in vitro elution model, tube samples were incubated in saline solution at 37.8 degrees C. In the in vitro adherence model, coated and uncoated tubes were exposed to 21 respiratory isolates of radiolabeled microorganisms for 2-4 hrs. In the animal model, 12 healthy white rabbits were intubated for 16 hrs with noncuffed silver-coated or uncoated tubes and challenged with buccal administration of Pseudomonas aeruginosa. In the in vitro assessment, tubes from 16 patients underwent quantitative culture assessment and qualitative confocal laser scanning microscopy. MEASUREMENTS AND MAIN RESULTS: After in vitro incubation, the mean residual silver concentration was 2.6 microg/cm, confirming that the coating was not entirely depleted. In vitro adherence to the silver-coated endotracheal tube was less than that of the uncoated tube for 12 of 21 isolates and equivalent for seven. For example, adherence to the silver-coated endotracheal tube was reduced >90% for all five isolates of P. aeruginosa (p < .05). In rabbits, P. aeruginosa colonization on the silver-coated endotracheal tube was reduced 99.9% compared with that on the uncoated tube (p < .0001); colonization in the tracheal and lung tissue was reduced > or =99% (p < .05). In the in vitro assessment, pathogens were detected on none of nine silver-coated tubes from patients and three of seven control tubes (p > .05). CONCLUSIONS: : The collective findings of this series of studies demonstrated that the silver-coated endotracheal tube was active in models designed to mimic the early pathogenesis of ventilator-associated pneumonia.
Subject(s)
Intubation, Intratracheal/instrumentation , Pneumonia, Ventilator-Associated/microbiology , Silver Compounds , Animals , Bacteria/isolation & purification , Bacteria/metabolism , Bacterial Adhesion , Disease Models, Animal , Equipment Contamination/prevention & control , Female , Humans , In Vitro Techniques , Intubation, Intratracheal/adverse effects , Pneumonia, Ventilator-Associated/prevention & control , Pseudomonas Infections/prevention & control , Rabbits , Silver SulfadiazineABSTRACT
Biofilm consists of microorganisms with altered phenotypes living in a self-organized, cooperative community attached to surfaces and each other and embedded in a self-produced matrix of exopolymer saccharides. Biofilms are relevant for home care and hospice clinicians because they are related to the majority of infectious diseases. Colonization of medical devices plays a key role in the problem of healthcare-associated infections. This article aims to provide an overview of the science of biofilms. Understanding biofilms and the risks associated with them is the first step toward prevention of biofilm formation and the potentially serious outcomes of infections.
Subject(s)
Biofilms , Cross Infection/etiology , Cross Infection/prevention & control , Equipment Contamination/prevention & control , Infection Control/methods , Bacterial Adhesion , Biofilms/growth & development , Catheterization, Central Venous , Catheterization, Peripheral/adverse effects , Catheterization, Peripheral/instrumentation , Catheters, Indwelling/adverse effects , Catheters, Indwelling/microbiology , Cross Infection/epidemiology , Drug Resistance, Microbial , Equipment Contamination/statistics & numerical data , Health Personnel/education , Health Planning Guidelines , Humans , Phenotype , Practice Guidelines as Topic , Prosthesis-Related Infections , Risk Factors , Urinary Catheterization/adverse effects , Urinary Catheterization/instrumentation , Urinary Catheterization/nursingABSTRACT
Usage of DNA vaccination has been limited by inefficient cellular expression of plasmid constructs used in DNA vaccines. We describe a novel system for enhancing delivery of DNA vaccine plasmids into cells and their nuclei. This delivery system uses recombinant reovirus type 3 sigma1 attachment protein genetically modified with a nuclear localization sequence (sigma1-NLS) as a targeting ligand. Purified sigma1-NLS was covalently conjugated to the polycation polyethyleneimine (PEI) using a carboxyl-reactive cross-linking agent and complexed with plasmid DNA. The benefit of the NLS in enhancement of protein delivery into the nucleus was demonstrated by liposome-mediated loading of cells with sigma1 or sigma1-NLS. In L929 fibroblasts loaded with sigma1-NLS, 69% of the internalized protein was recovered in the nuclear fraction after 6 h compared to just 10% when using unmodified sigma1. Transfection of L929 cells with sigma1-NLS-conjugated PEI complexed with a luciferase expression plasmid resulted in a mean 16-fold increase in luciferase activity over complexes made with unmodified PEI, compared to a mean 3-fold boost obtained using sigma1-conjugated PEI. These results suggest that sigma1-NLS is a useful bifunctional targeting ligand suitable for enhancing DNA delivery and subsequent gene expression for both DNA vaccine applications and nonviral gene therapy.
