Reducing Infections Using Nanotechnology
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Reducing Infections Using Nanotechnology Thomas J. Webster1,2* 1
Department of Chemical Engineering, Northeastern University, Boston, MA, 02115, USA Center of Excellence for Advanced Materials Research, King Abdulaziz University, Jeddah, Saudi Arabia 2
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 infection could help prevent this problem. The objective of this study was to determine differences in the growth of Staphylococcus aureus (S. aureus) on nanomodified and unmodified polyvinyl chloride (PVC) ETTs under dynamic airway conditions. 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 air flow conditions within the ETT influenced both the location and 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 to the conventional ETTs after 24 hours of air flow. This dynamic study showed that lipase etching can create nano-rough surface features on PVC ETTs that suppress S. aureus growth and, thus, may provide clinicians with an effective and inexpensive tool to combat VAP. INTRODUCTION Despite extensive research into prevention and management, ventilator associated pneumonia (VAP) continues to be a severe, costly complication of mechanical ventilation among critically ill patients. Device related infections, such as VAP affect 28% of the patients who use mechanical ventilation. In the United States, the estimated yearly cost of hospital acquired infections (HAIs), such as VAP, can be up to 6.7 billion dollars [1]. The two pathogens most commonly associated with VAP are Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus) [2]. VAP presents a particular intractable problem to the pediatric ICU because it is often difficult to distinguish pneumonia from other respiratory conditions common in mechanically ventilated patients [3]. This is especially true in ventilated neonates and can cause delays in targeted treatment or the prolonged use of a broad- spectrum of antibiotics leading to serious risks such as the development of multidrug resistant organisms [1]. One of the main sources of bacterial colonization within the airway is the endotracheal tube (ETT). ETTs are of special concern because these tubes provide a direct conduit from the outside environment to the lungs [4] [5]. Aggregations of microorganisms surrounded by extracellular matrix (or biofilms) on the surface of the ETT make treatment difficult as they are especially resistant to both antibiotics and the immune system of the patient.
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