Biofilm formation in acute and chronic wounds is associated with delayed wound healing, inflammation, and infection, and therefore pose a large burden on health care. Once formed, biofilms exhibit an increased tolerance to antimicrobials in comparison to their planktonic counterparts and are consequently difficult to treat. Effective antimicrobials are needed to eradicate biofilms from wounds. The aim of this study was to evaluate the antibiofilm efficacy of a concentrated surfactant gel (CSG) with and without 1% silver sulfadiazine (SSD) against Pseudomonas aeruginosa biofilm in a relevant in vitro biofilm model.
An in vitro wound model using pig skin obtained from a local abattoir was set up to evaluate the efficacy of wound dressings against P. aeruginosa using the drip flow biofilm model. An overnight culture of P. aeruginosa was adjusted to 0.5 McFarland (1 x 108 CFU/mL) and used to inoculate pig skin in the drip flow bioreactor. The inoculated pig skin was incubated in continuous flow phase for 24 hours. Biofilms were washed with 10 mM phosphate buffered saline (PBS) to remove planktonic cells and treated with the CSG and CSG-SSD for a further 24 hours. Pig skin was then added to neutralizing broth and sonicated. Samples were serial diluted in 10 mM PBS and plated onto Tryptone Soya agar (TSA) in duplicate. Plates were incubated at 37°C overnight and the following day bacterial colonies were enumerated.
Following 24-hour treatment with the CSG and CSG-SSD, a reduction in biofilm cell density was found in comparison to an untreated control. The results demonstrate anti-biofilm efficacy of the CSG-SSD in an in vitro wound care model and support the use of this CSG in wound care.