The broad-spectrum kayvirus phage disrupts biofilms formed by methicillin-resistant Staphylococcus aureus and methicillin-resistant Staphylococcus pseudintermedius

The escalating global challenge of methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus pseudintermedius (MRSP) demands innovative therapeutic approaches. This study comprehensively characterized Staphylococcus phage vB_SauM_VL14 (VL14), a virulent bacteriophage from the Herelleviridae family (Twortvirinae subfamily, Kayvirus genus) with a 141,584-bp linear double-stranded DNA genome. Genomic analysis confirmed that phage VL14 is strictly lytic, containing 224 ORFs and four tRNAs, without lysogenic, virulence, or antimicrobial resistance genes. Phage VL14 demonstrated a 30-min latent period with a burst size of 110 PFU. Host range analysis revealed broad activity, lysing 100 % of S. aureus and 60 % of S. pseudintermedius isolates, including methicillin-resistant strains. The phage achieved significant bacterial reductions and exhibited remarkable biofilm-disrupting capabilities, substantially reducing the biofilm mass and viable cell counts. These findings establish phage VL14 as a broad-spectrum lytic phage with potent bactericidal and biofilm-disrupting activity, supporting its potential as a therapeutic agent against multidrug-resistant Staphylococcus infections and warranting further evaluation in in vivo and clinical settings.