New Proteins from Cold: Antibiofilm Activity of Cold-Azurin and PsyOmp38 Against Enterococcus faecalis and Klebsiella pneumoniae

In the present study, attention was given to Enterococcus faecalis and Klebsiella pneumoniae commonly causing healthcare-associated infections highly recalcitrant to antimicrobial therapy, also for their ability to form biofilms. These pathogens are often associated with a high risk of urinary tract infections due to biofilm-related complications in indwelling devices, commonly used in urological surgery. Currently, research is focusing on the development of new therapeutic strategies aimed at targeting bacterial virulence factors, such as biofilm, to reduce the increasing development of multidrug-resistant pathogens. In the present research, the activity of two antibiofilm proteins deriving from Antarctic marine bacteria, PsyOmp38 and Cold-Azurin, was evaluated on a collection of clinical E. faecalis and K. pneumoniae strains. In particular, the antibiofilm capabilities of PsyOmp38 and Cold-Azurin were tested against clinical bacterial strains characterized by different antimicrobial resistant profiles during distinctive phasis of biofilm development: initial attachment to the surface, pre-adhesion period and mature biofilm. This study provides interesting insights into the mechanism of action of the two proteins at different stages of the biofilm. Both proteins are able to impair, with different capabilities, biofilm formation of almost all bacterial tested strains. While Cold-Azurin disrupts mature biofilm only in a limited number of bacterial strains, PsyOmp38 shows disrupting activity against all Klebsiella strains and almost all E. faecalis strains. These findings suggest that Antarctic-derived proteins, particularly PsyOmp38, may represent promising candidates for the development of novel antibiofilm strategies against multidrug-resistant ESKAPE pathogens.