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Inhibition of bacteriophage K proliferation on Staphylococcus aureus in raw bovine milk

S O'Flaherty1, A Coffey, W J Meaney

  • 1Dairy Products Research Centre, Teagasc, Moorepark, Fermoy, Co., Cork, Ireland.

Letters in Applied Microbiology
|August 20, 2005
PubMed
Abstract

Insights

Staphylococcal bacteriophage K cannot effectively inhibit Staphylococcus aureus in raw milk because the raw milk environment prevents phage replication. Heat treatment of milk restores the bacteriophage

Area of Science:

  • Microbiology
  • Food Science
  • Bacteriophage Therapy

Background:

  • Bacteriophages (phages) show potential as therapeutic agents against bacterial infections, including those caused by Staphylococcus aureus.
  • The efficacy of phage therapy in milk-based environments, such as for bovine mastitis, depends on phage viability and replication within milk.
  • Raw milk contains various components that may influence phage-host interactions and phage proliferation.

Purpose of the Study:

  • To evaluate the efficacy of staphylococcal bacteriophage K in inhibiting Staphylococcus aureus within raw milk.
  • To investigate the factors in raw milk that may affect bacteriophage replication and adsorption.
  • To understand the implications for using bacteriophage therapy in milk.

Main Methods:

  • Assessed bacteriophage K replication and host elimination in both raw and heat-treated milk.
  • Quantified phage adsorption rates to Staphylococcus aureus in different milk matrices using adsorption assays.
  • Utilized confocal microscopy with Live/Dead Bac light staining to visualize bacterial distribution and morphology in raw versus heat-treated milk.

Main Results:

  • Staphylococcal bacteriophage K replicated effectively and eliminated Staphylococcus aureus in heat-treated milk.
  • Phage replication and adsorption were significantly inhibited in raw milk, with adsorption reduced from 99.96% to 86.50%.
  • Confocal microscopy revealed Staphylococcus aureus forming clusters associated with fat globules in raw milk, unlike in heat-treated milk.

Conclusions:

  • Raw milk significantly inhibits the proliferation of staphylococcal bacteriophage K.
  • The physical and chemical properties of raw milk, potentially related to fat globules, impede phage activity.
  • These findings suggest limitations for the direct application of staphylococcal therapeutic phages in raw milk environments.

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