Klebsiella pneumoniae can cause bovine mastitis and contaminate dairy products, posing risks to animal health and food safety. Conducted as part of the ICARS-supported MOB-TARGET project, this study investigated whether bacteriophages, viruses that selectively infect bacteria, could control multidrug-resistant, hypervirulent K. pneumoniae from dairy sources.
Researchers isolated two phages from dairy-farm wastewater that target different receptors on the bacterial surface. A cocktail combining the phages demonstrated greater bactericidal activity than either phage alone in pasteurised milk and a mouse model of mastitis, reducing bacterial loads and tissue inflammation. The treatment also promoted the emergence of phage-resistant mutants with capsule defects. These mutants showed reduced virulence, including weaker biofilm formation, impaired adhesion to host cells, loss of serum resistance and greater susceptibility to phagocytosis.
The findings suggest that this phage cocktail could provide two complementary benefits: directly killing multidrug-resistant K. pneumoniae and selecting for phage-resistant bacteria that are less able to cause disease. Further research would be needed to assess its safety and effectiveness in dairy cattle and farm settings.
