In vitro study on endotoxin release of gram-negative bacteria after contact with silver releasing compared to DACC coated wound dressings

The treatment of critically colonised or locally infected wounds with local antimicrobial agents is a standard of care. The destruction of especially gram-negative bacteria potentially increases the endotoxin level in the wound. This in vitro study aims to answer the question of whether and to what extent endotoxin release caused by the destruction of gram-negative bacteria is influenced by different wound dressing. Silver ion releasing dressings were compared to wound dressings with hydrophobic effect coated with dialkyl carbamoyl chloride (DACC). In addition, the bactericidal efficacy was measured. The log10 reduction factors (RF) against Pseudomonas aeruginosa were between 0 and 0.9 for the hydrophobic dressings and 8.7 for the silver releasing dressing. The bacterial endotoxin content of the agar located under the dressing after contamination with P. aeruginosa was >300 <3000 IU/ml in the case of a cotton gauze (control), >3000 <30,000 IU/ml for DACC coated distance grid, >30 <300 IU/ml in for the DACC coated foam dressing and >0.3 <3 IU/ml in the case of the silver ion releasing dressing. The content of bacterial endotoxins which could be extracted from the wound dressing after contact with P. aeruginosa was >30,000 <300,000 IU/ml for the control dressing, >30,000 <300,000 IU/ml in the case of Cutimed Sorbact, >3000 <30,000 IU/ml for the DACC coated foam dressing and >3 <30 IU/ml for the silver-releasing dressing. According to these findings, the silver ion releasing dressing has a higher antibacterial effect than wound dressings coated with DACC and it also releases a significantly lower amount of bacterial endotoxins.