Evaluation of Antimicrobial Properties of an Iodine Foam Dressing and Two Gentian Violet/Methylene Blue Foam Dressings

Effective antimicrobials are required to treat complicated infections and chronic wounds. The purpose of the study was to evaluate the antibacterial activities of an iodophor of iodine/polymer foam dressing (IF) and two gentian violet/methylene blue foams (BF1 and BF2) after 5 minutes, 30 minutes, 3 days, and 7 days exposure times against MRSA.

Each sample and a control were tested in triplicate at T=0, T=5 minutes, T=30 minutes, T=3 days, and T=7 days. The samples were inoculated with 1mL of 10⁶ CFU/mL MRSA suspension. For the T=0 samples, the foam samples were neutralized with D/E broth immediately after inoculation and enumerated. For T=5 minutes and 30 minutes, the samples were neutralized and enumerated at the respective time points. For T=3 days and T=7 days, the samples were placed in a 35-39°C/70% minimum humidity chamber until the time points were reached. However, the T=7 days samples were re-inoculated with 0.1mL of 10⁷ CFU/mL MRSA on the first and fourth day.

At T=0, there was no log reduction. At T=5 minutes, IF had a 4.74 log reduction of MRSA, while BF1 and BF2 showed no reduction of MRSA. At T=30 minutes, IF had a 4.75 log reduction of MRSA, while BF1 and BF2 showed no reduction of MRSA. At T=3 days, IF and BF1 both had a 4.05 log reduction of MRSA, while BF2 showed no reduction of MRSA. At T=7 days, IF and BF2 both had a 5.04 log reduction of MRSA, while BF1 showed no reduction of MRSA.

The IF showed a greater than 4-log kill of MRSA at T=5 minutes, 30 minutes, 3 days and 7 days. BF1 only showed a greater than 4-log kill at T=3 days, and BF2 only had a greater than 4-log kill at T= 7 days.