Prevalence of bacteriophages infecting Staphylococcus aureus in dairy samples and their potential as biocontrol agents

Random amplification of polymorphic DNA (RAPD)-PCR profiles of bovine Staphylococcus aureus isolates obtained with the oligonucleotide RAPD5 and the similarity dendrogram generated by the unweighted pair group method with arithmetic averages.

Inhibitory activity of single phages and the phage mixture (10⁴ to 10⁵ pfu/mL) against Staphylococcus aureus Sa9 at 37°C in UHT whole-fat milk: ◊=Staph. aureus, ■=Staph. aureus + ΦA72, ▴=Staph. aureus + ΦH5, ●=Staph. aureus + ΦA72 + ΦH5.

Antibacterial activity of phages ΦH5 and ΦA72 against Staphylococcus aureus Sa9 at 37°C in A) pasteurized whole-fat milk, B) semi-skimmed raw milk, and C) whole-fat raw milk. □=Staph. aureus, ■=Staph. aureus + ΦA72+ ΦH5,×=phage titer.

Inhibitory activity of a mixture of phages ΦH5 and ΦA72 against Staphylococcus aureus Sa9 in UHT whole-fat milk during a simulated breakdown in the cold chain. Incubation proceeded at 4°C for 18h, shifted to 22°C, and was maintained there for 30h. A) Growth of Staph. aureus Sa9 (♦=Staph. aureus, ■=Staph. aureus + phages ΦH5 and ΦA72 (10¹ pfu/mL), ▴=Staph. aureus + phages ΦH5 and ΦA72 (10² pfu/mL), □=Staph. aureus + phages ΦH5 and ΦA72 (10⁴ pfu/mL); B) titer of bacteriophages in samples in which phages were added at initial concentrations of 10¹ pfu/mL (■), 10² pfu/mL (▴), or 10⁴ pfu/mL (□).