NEW APPROACHES IN THE TREATMENT OF CHRONIC BACTERIAL INFECTIONS

Abstract

The rapid emergence and spread of multidrug- resistant pathogens present a global healthcare challenge. One common cause of resistance and/or tolerance to antibiotics is biofilms, a complex communities of bacteria embedded in a self-produced matrix. Biofilm formation and maturation are regulated by quorum sensing, a cell density-dependent communication system that relies on the synthesis, diffusion, and detection of small signaling molecules - autoinducers (AIs). Quorum quenching (QQ) enzymes that cut Ais emerged as a promising strategy for persistent bacterial infections. However, a significant drawback for the use of QQ enzymes as therapeutics is their poor stability and efficacy in vivo. Since one of the major health issues linked to biofilm development is persistent wound infections, our goal was to improve enzyme properties by immobilizing it on a natural biopolymer to make it suitable for use as a wound dressing. The best candidate for immobilization was YtnP lactonase from Bacillus paralicheniformis ZP1, as in concentrations higher than 25 μg/mL it improved the survival of Pseudomonas aeruginosa PAO1-infected zebrafish, rescuing 80% of embryos. When combined with tobramycin or gentamicin, the survival rate of zebrafish embryos increased to 100%. Purified YtnP lactonase at a concentration of 1 mg was immobilized on 10 mg of polymer disks by crosslinking with glutaraldehyde. Specific modifications of the polymer were also made to eliminate the use of glutaraldehyde, which is a skin irritant. In in vivo experiments on a murine chronic wound model, immobilized enzyme inhibited biofilm development, cleared already formed biofilms, and overall improved wound healing. These results provide a foundation for the development of advanced wound dressings that will prevent infection development in wounds and enable proper therapy for infected chronic wounds.