Antibacterial Properties of Various Gelling Fiber Wound Dressings against Methicillin Resistant Staphylococcus aureus and Pseudomonas aeruginosa

A wide range of dressings exists to cater to the varying requirements of acute and chronic wounds. Gelling fiber dressings assist with moisture balance by transforming absorbent fibers into a conformable gel, while also managing wound drainage and exudate. Some chitosan-containing dressings may help to control bleeding by promoting coagulation. Additionally, some dressings contain antibacterial components, including silver ions. Following modified standard AATCC 100 (2019), time kill procedures were performed to evaluate the antibacterial efficacy of four gelling fiber wound dressings against Pseudomonas aeruginosa (ATCC 9027) and methicillin resistant Staphylococcus aureus (MRSA)(ATCC 33591) in simulated wound fluid (SWF). Samples were aseptically cut into 2x2 inch sections. Some dressings were immediately challenged with microbes in SWF and then neutralized and enumerated 6 or 24 hours later. Other samples were pre-conditioned with SWF for 7 days, with re-conditioning at days 3 and 5, inoculated at day 7, and then neutralized and enumerated 24 hours later. All samples were tested in triplicate and mean Log10 reductions were calculated between inactive parallel control* and test samples&,$,%,+. Results indicate that all test samples achieved greater than a mean 4 Log10 reduction against P. aeruginosa. However, only the gelling fiber wound dressing with silver and chitosan& achieved greater than a mean 4 Log10 reduction against MRSA when pre-conditioned for 7 days prior to the 24 hour microbial exposure. In contrast, one comparator dressing$ achieved greater than a mean 4 Log10 reduction at 6 and 24 hours post-inoculation but not in the context of pre-conditioning, and the others never achieved greater than 4 log kill%,+ against MRSA. These data highlight key differences in antibacterial killing effectiveness and demonstrate superiority of the chitosan-containing gelling fiber dressing&.