Antibiofilm Efficacy of an Iodine Dressing in Comparison to Other Antibacterial Dressings Against Immature and Mature Biofilms

Abstract Body: Biofilms can form on surfaces, such as medical devices and wounds, leading to infection, inflammation and delayed wound healing. Unlike their planktonic counterparts, biofilms are recalcitrant to antibiotics, making them difficult to treat and contributing to formation of non-healing wounds. The aim of this study was to evaluate a new iodine dressing for antibiofilm efficacy against Staphylococcus aureus and Pseudomonas aeruginosa 24-hour (immature) and 48-hour (mature) biofilms to compare its efficacy to other commercial wound dressings which contain either silver or organic pigments.   Antibiofilm efficacy was evaluated following an adapted version of ASTM E2871-13 ‘Standard test method for evaluating disinfectant efficacy against Pseudomonas aeruginosa biofilm grown in CDC biofilm reactor using single tube method’. Following biofilm growth, coupons were individually wrapped in the dressings and incubated for 24 hours. Then, coupons were added to 10 mL of a broad-spectrum neutraliser, sonicated, serial diluted 1:10 and plated onto TSA. Plates were incubated at 37°C overnight and the following day colony counts were enumerated.   Following 24-hour treatment of a 24 hour biofilm of S. aureus with an iodine dressing and a nanocrystalline silver dressing, no growth was observed, showing an 8-log reduction in bacterial density (p 0.006). Additionally, antibiofilm efficacy was observed following treatment of the 48 hour biofilm of S. aureus with an iodine dressing and nanocrystalline silver dressing. Following 24-hour treatment of a 24 hour biofilm and a 48 hour biofilm of P. aeruginosa with an iodine dressing and nanocrystalline silver dressing no bacterial growth was observed, showing an 8-log reduction (p 0.0382) and 9-log reduction (p 0.0135) in bacterial cell density, respectively.   The iodine dressing shows potent antibiofilm efficacy against representative Gram-positive and Gram-negative 24-hour (immature) and 48-hour (mature) biofilms in vitro. The data shows the potential for the iodine dressing to treat and eradicate biofilms.