Further Observations on Changes in the Phage-Typing Pattern of Phage Type 80/81 Staphylococci

Abstract
Two distinct temperate phages (594a, 594n) lysogenizing phage type 80/81 staphylococci and producing gains in sensitivity to typing phages 52 and 52A were found in lysogenic clones of a strain of staphylococcus of phage type 52/52A/-80/81. When either of these phages infected type 80/81 cocci a new phage (594b) appeared in the lysates. This phage was unable to replicate in type 80/81 cocci but could grow in them when they had been lysogenized with phage 594a or 594n. The source of phage 594b was found to be recombination of phage 594a or 594n with a prophage present in cocci of phage type 80/81. This prophage was completely defective and could be demonstrated only by recombination. The gains in phage sensitivity that follow lysogenization of type 80/81 strains with the so-called "converting" phages can be most satisfactorily explained on the basis of prophage substitution.