Fourteen-Day Evaluation of the Antibacterial Activity of Two Post-Operative Surgical Dressings Against MRSA

Purpose: The main purposes of surgical dressings are to control any postoperative bleeding, absorb exudate if anticipated, ease pain and provide protection from pathogens for newly formed tissue. These dressings typically have a seven-day wear time, but testing was conducted to stress the dressings’ antibacterial abilities beyond their typical wear time. The purpose of the study was to compare the antibacterial activity of two post-operative surgical dressings against Methicillin Resistant Staphylococcus aureus (MRSA) at 14 days. 

Methods: The test materials (OG, OG-Control, PS, PS-Control) were cut into 2 x 2 inch sections and aseptically placed into sterile containers until initial inoculation. The initial inoculum volume was 1 mL of 2.46 x 106 CFU/mL MRSA, and it was absorbed by the samples without over-saturating them. The T = 0 samples were immediately neutralized and enumerated. The T = 14 days samples were placed in the 35-39◦C/70% RH chamber. They were re-inoculated on days 4, 8 and 11 with 1ml of 1.2 x 106 CFU/mL and placed back in the chamber. At T=14 days, the samples were neutralized and enumerated. 

Results: At T = 0, the Log10 reduction was 0.00 for all tested samples. At T=14 days after 3 repeat inoculations, the Log10 reduction was 0.00 for both controls (OG-Control and PS-Control), and both OG and PS achieved a greater than 4 Log reduction.

Conclusion: Both post-operative surgical dressings showed effective antibacterial properties against MRSA in vitro.