Controlled Release of LL-37-Derived Synthetic Antimicrobial and Anti-Biofilm Peptides SAAP-145 and SAAP-276 Prevents Experimental Biomaterial-Associated Staphylococcus aureus Infection

The present study aims to develop an implant coating releasing novel antimicrobial agents to prevent biomaterial-associated infections. The LL-37-derived synthetic antimicrobial and anti-biofilm peptides (SAAP)-145 and SAAP-276 exhibit potent bactericidal and anti-biofilm activities against clinical and multidrug-resistant Staphylococcus aureus strains by rapid membrane permeabilization, without inducing resistance. Injection of SAAP-145, but not SAAP-276, along subcutaneous implants in mice reduces S. aureus implant colonization by approximately 2 log, but does not reduce bacterial numbers in surrounding tissue. To improve their efficacy, SAAP-145 and SAAP-276 are incorporated in a polymer-lipid encapsulation matrix (PLEX) coating, providing a constant release of 0.6% daily up to 30 d after an initial burst release of >50%. In a murine model for biomaterial-associated infection, SAAP-145-PLEX and SAAP-276-PLEX coatings significantly reduce the number of culture positive implants and show >= 3.5 and >= 1.5 log lower S. aureus implant and tissue colonization, respectively. Interestingly, these peptide coatings are also highly effective against multidrug-resistant S. aureus, both reducing implant colonization by >= 2 log. SAAP-276-PLEX additionally reduces tissue colonization by 1 log. Together, the peptide-releasing PLEX coatings hold promise for further development as an alternative to coatings releasing conventional antibiotics to prevent biomaterial-associated infections.