Purification, fine structure and characterization of temperate phages from drug-resistant Staphylococcus aureus

Three kinds of temperate Staphylococcus aureus phages were differentiated by serological, sedimentation and electron microscopic studies. Phage S1 had a long hexagonal head and a long tail, a density in Cs2SO4 of 1.364 g/ml and belonged to serological group A; phage S2 had a short hexagonal head and a short tail, a density of 1.385 to 1.392 g/ml and belonged to serological group B; phage S3 had a shape similar to phage S2 except for some minor differences, but had a density of 1.416 g/ml and belonged to serological group F. S. aureus MS27 was found to be singly lysogenic for S2. However, S. aureus MS3878 was a doubly lysogenic strain carrying S1 and S2 and S. aureus E169 was a triply lysogenic strain carrying S1, S2 and S3. All these temperate phages showed similarity in shape to typing phages belonging to the same serological group. The temperate S. aureus phages revealed the presence of a hexagonal baseplate with spikes. The burst sizes of phages of S1, S2 and S3 were about 50, 110 and 120 respectively. The DNA from S1, S2 and S3 ranged from 29.4 to 30 megadaltons in size.