1 INTRODUCTION
National Pressure Ulcer Advisory Panel (NPUAP) defined pressure ulcers as locally damaged soft tissue or skin over a bony part or due to a device (Unver et al., 2017). In the United States, pressure ulcers have affected about 2.5 million patients annually and the treatments are estimated to cost between 9 and 11.5 billion dollars. Due to a direct result of pressure ulcers, about 60,000 patients died annually (Zapirain et al., 2017). Pressure ulcers are often associated with disabilities where 70% of the time occurring in people above 70 years old. Prolonged periods of recovery are due to chronic deep wounds suffered by several elderly patients. The mortality rate of patients who suffered from serious infective complications such as bacteremia was reported to be greater than 50%. Even though preventable, pressure ulcer is a common find in bed-ridden, elderly patients who are immobilized by their acute illness. The percentage is foretold to be more than 11% of the population by 2020 (Khor et al., 2014). As the skin damages, it loses its functions such as preventing water vapor loss, physical protection and thermal regulators. In this situation, wound infection is better prevented by declining bacterial entry into the open wound rather.
The microorganisms recurrently found in colonized pressure ulcers areStaphylococcus aureus and Gram-negative bacilli such as Enterobacteriaceae, Acinetobacter baumannii and Pseudomonas aeruginosa . The patients possessing colonized ulcers with developing infections are often seriously ill (Braga et al., 2013). Consequently, this leads to prolonged hospital stays and the need to use invasive medical devices such as central vascular catheter, tracheal tube and urinary catheter.To tackle the issue, a range of wound dressing products were created in order to return the functions to damaged skin (Vowden & Vowden, 2017). Unfortunately, these wound dressings come with their fair share of drawbacks. Silver wound dressings have been reported to cause argyria from extensive use of silver-containing wound dressing materials and medications (Berger et al., 2013). In addition to anti-inflammatory effects, nanosilver has been shown to control collagen deposition leading to a proper alignment of collagen fibrils that accelerates wound healing and have shown their efficacy in bypassing drug-resistance mechanisms (Song et al., 2015).
In wound healing, the wound dressing acts as a protection to the wound while the dermal and epidermal tissues heal. Thus, natural polymers such as polysaccharides; chitosan, alginates, heparin, and cellulose are widely selected in wound treatments and management because they are biologically compatible, biodegradable and similar to macromolecules that are familiar to the human body (Capanema et al., 2017). Phomopsidione (C7H10O4) is a novel ketone derivative isolated from Diaporthe flaxiniiED2. In this study, we designed a chitosan-polyethylene glycol (PEG) nanocomposite wound dressing hydrogel using phomopsidione as antimicrobial finishing. The mechanical and physical properties of the developed hydrogel were characterized and in vitro antimicrobial efficiency of the hydrogel was evaluated on the clinical wound microorganisms.