Combined use of bacteriophage K and a novel bacteriophage to reduce Staphylococcus aureus biofilm

Biofilms are major causes of impairment of wound healing and patient morbidity. One of the most common and aggressive wound pathogens is Staphylococcus aureus, displaying a a large repertoire of virulence factors and commonly reduced susceptibility to antibiotics, such as the spread of methicillin-resistant S. aureus (MRSA). Bacteriophages are obligate parasites of bacteria. They multiply intracellularly and lyse their bacterial host releasing their progeny. We isolated a novel phage, DRA88 that has a broad host range amongst S. aureus. Morphologically the phage belongs to the Myoviridae family and comprises a large dsDNA genome of 141,907 bp. DRA88 was mixed with phage K to produce a high titre mixture that showed strong lytic activity against a wide range of S. aureus isolates including representatives of the major international MRSA clones and coagulase-negative Staphylococcus. Its efficacy was assessed both in planktonic cultures and when treating established biofilms produced by three different biofilm producing S. aureus isolates. A significant reduction of biofilm biomass over 48 hours of treatment was recorded in all cases. The phage mixture may form the basis of an effective treatment for infectious caused by S. aureus biofilms.