Assessing the effect of an antimicrobial wound dressing on biofilms.

To date the effect of silver-containing wound dressings on biofilms, known to be present in chronic wounds, has not been determined or documented. In this current study, we aimed to determine the antimicrobial effect of a silver-containing dressing on biofilms grown in a chambered slide model. Before the addition of a wound dressing onto a 24-hour biofilm, composed of either Pseudomonas aeruginosa, Enterobacter cloacae, Staphylococcus aureus, or a mixed bacterial community, a fluorescent dye was applied. This enabled the viability of sessile bacteria to be monitored in real-time, using a rapid form of confocal laser scanning microscopy over a contact time period of 48 hours. By analyzing all the three-dimensional data generated from the confocal time-lapse sequences, 90% of all sessile bacteria within the biofilm were observed to progressively turn red (i.e., died) within 24 hours. Total bacterial kill in the biofilm was achieved after 48 hours. This research has shown that the dressing was effective in killing the tested bacteria evident in both the tested mono and polymicrobial biofilms, which provides valuable evidence that this dressing may have an effect on biofilms found in recalcitrant chronic wounds.