Characterization of two novel lytic bacteriophages for reducing biofilms of zoonotic multidrug-resistant Staphylococcus aureus and controlling their growth in milk

This study targeting the characterization of new lytic phages and studying their impact on Staphylococcus aureus biofilm and growth in milk. Two lytic phages (vB_SauM_ME18 & vB_SauM_ME126) were isolated using 40 Multidrug-Resistant (MDR) S. aureus isolates. Four isolates (10%) were susceptible to phages. Phages were related to Family Myoviridae, had icosahedral heads and long contractile tails. The genome size is 20 kbp for both phages and DNA was digested with hinf I, hind III and hae III. Phages had a latent period (similar to 15 min), rise period (similar to 30 min) and burst size (114 PFU/infected cell for ME18 and 140 PFU/infected cell for ME126). There was a significant reduction in biofilm formation and reduction in the established biofilm biomass in phage treated S. aureus compared with controls (P < 0.05). Phages showed high activity and eliminated MDR S. aureus from ultra-heat-temperature treated milk at 25 degrees C. However, at 37 degrees C, ME126 (MOI1O) eradicated S. aureus and ME18 (MOI1O) reduced the CFU/ml by 87.2% compared with controls (P < 0.05). In essence, lytic phages are promising natural antimicrobials for inhibiting the growth and biofilm of MDR S. aureus in milk, thereby, biocontrol of foodborne pathogens.