Recombinant R2-pyocin cream is effective in treating Pseudomonas aeruginosa-infected wounds
<i>Pseudomonas aeruginosa</i>, a Gram-negative opportunistic pathogen, is one of the major species isolated from infected chronic wounds. The multidrug resistance exhibited by <i>P. aeruginosa</i> plus its ability to form biofilms that are difficult to eradicate, along with rising cost of producing new antibiotics, has necessitated the search for alternatives to standard antibiotics. Pyocins are antimicrobial compounds produced by P. aeruginosa to protect itself from competitors. We synthesized and purified recombinant <i>P. aeruginosa</i> R2 pyocin and used it in aqueous solution (rR2P) or formulated in polyethylene glycol (rR2PC) to treat P. aeruginosa-infected wounds. Clinical strains of <i>P. aeruginosa</i> were found to be sensitive (completely), partially sensitive, or resistant to rR2P. In the in vitro biofilm model, rR2P inhibited biofilm development by rR2P-sensitive isolates; while rR2PC eliminated partial biofilms formed by these strains in the in vitro wound biofilm model. In the murine model of excision wound, and at 24 h post infection, rR2PC application significantly reduced the bioburden of clinical isolate BPI86. Application of rR2PC containing two glycoside hydrolase antibiofilm agents eliminated BPI86 from the infected wound. These results suggest that the topical application of rR2PC is an effective therapy to treat wounds infected with R2P-senstive P. aeruginosa strains.