SAP-containing dressings exhibit sustained antimicrobial effects over 7 days in vitro

OBJECTIVE: To investigate the antimicrobial activity of SAP-containing wound dressings in vitro over a prolonged period of time (7 days) and to assess their ability to sustain the antimicrobial effect. METHOD: SAP dressings were tested according to the JIS L 1902:2002 against the pathogens Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli and Candida albicans.Additionally, effect on S. aureus and P. aeruginosa growth was investigated after a prolonged incubation period of 7 days. Furthermore, both SAP dressings were repeatedly inoculated with P. aeruginosa suspension and, after 7 days, microbial growth under the dressings was evaluated. RESULTS: Both SAP-containing wound dressings tested exhibited a significant to strong antimicrobial activity against Staphylococcus aureus, MRSA, Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, and Candida albicans in vitro. Moreover, it could be shown that they were able to sustain antibacterial efficacy over a prolonged period of time. Using a direct incubation method with repeated re-inoculation of the dressing samples, it could be shown that growth of P. aeruginosa was reduced after 4 days of treatment and completely inhibited after 7 days. No significant differences were observed between the two SAP-dressings tested. CONCLUSION: These in vitro experiments impressively demonstrated the antimicrobial mechanism of SAP-containing wound dressings: rapid up-take of fluid, binding of microorganisms to the SAP-core, and retention of the bacteria inside the dressing. Moreover, it could be shown that they are able to exhibit their antimicrobial activity over a prolonged period of time unless the amount of fluid present exceeds their fluid-handling capacity.