Isolation, functional characterization and antibiofilm properties of a lytic Enterococcus phage RG1 against multidrug resistant E. faecium

Enterococcus faecium, a multidrug-resistant (MDR), commensal human pathogen, frequently causes nosocomial infections and imposes serious threat to public health, which demanded more research for the development of alternative therapeutics against them. Bacteriophage therapy as an alternative to antibiotics has reappeared as therapeutics against MDR bacterial infections. Here, we isolated and characterized a novel lytic phage, RG1, from the Ganga River against E. faecium ATCC 35667 and checked their efficacy against several clinical isolates of E. faecium. Whole genome sequencing revealed that the RG1 belongs to genus Efemquintavirus, and has a dsDNA genome of 41,364 base pairs with 35.54% GC content, which encodes 65 putative open reading frames without any virulence, antibiotic resistance or lysogeny genes. Bacteriophage RG1 displayed high stability across different pH, temperatures and chloroform concentrations. The phage RG1 exhibited antibacterial and antibiofilm activity over both ATCC and clinical isolates of E. faecium likely due to its wider host range, which paves the way inside the precision phage therapy. Interestingly, the presence of ribose, maltose and trehalose sugars showed more suppression of bacterial growth of MDR E. faecium isolate in presence of the phage RG1, while sugar alcohols synergistically supported host lysis by this phage. These findings highlight the therapeutic potential of the phage RG1 against the MDR E. faecium under clinical setup.