Long-Term Antimicrobial Efficacy of a Novel Composite Dressing

A composite dressing generating microcurrent has been developed for improved wound healing and for treating hard-to-treat wound infectious including antibiotic-resistant pathogens. The American Association of Textile Chemists and Colorists’ (AATCC) standard test method 100 provides a quantitative procedure to evaluate the degree of antimicrobial activity of treated finishes on or in textile materials. Composite dressing (CD) was tested against multiple wound pathogens to determine the degree of antimicrobial activity after seven days of simulated use using the modified AATCC Test Method 100.

Treated and controls were exposed to Acinetobacter baumannii, Enterococcus faecalis, Klebsiella pneumoniae, MRSA, Pseudomonas aeruginosa, and Staphylococcus epidermidis. The long-term antimicrobial efficacy was assessed by comparing the surviving organisms from the untreated samples at initial contact time to surviving organisms from the untreated and treated samples at final time point after seven days of simulated use.

All test articles were pre-hydrated with sterile saline (0.9% NaCl) to activate microcurrents and inoculated with the culture suspension (~5 x 106 CFU/ml). The samples were immediately neutralized with D/E broth and serially diluted to count colonies on the agar plates after 24-hour incubation at 37°C. The other remaining samples were hydrated for day 0 with sterile saline and daily rehydrated for day 1 through day 6 with simulated wound fluid (SWF). On day 7, the cultures were inoculated and incubated at 37°C for 24 hours. The log reduction were calculated as follows: Log Reduction = Log10 (U0)- Log10 (Tt). U0 = the number of bacteria recovered from the inoculated (untreated blank) sample immediately after inoculation (initial contact time), Ut = the number of bacteria recovered from the inoculated sample on day 8 (final contact time).

The test articles showed significant bacterial reduction (~4–5.6 logs) over an extended time. This dressing is a promising technology for treating wounds and improving patients’ clinical outcome.