Studies on lysogeny in staphylococci.

A staphylococcus typing phage (NCTC 8426) was found to form lysogenic systems with three strains of staphylococci. In the case of two of these strains, staphylococci lysogenically infected with the typing phage were now lysed by the temperate phages they had previously carried. This loss of immunity was due to the replacement of the originally carried prophage by the prophage of phage 8426. This process could be reversed. With the third strain of staphylococcus the lysogenic offspring were not lysed by their original temperate phage, which they continued to carry. The NCTC phage 8426 appeared to undergo a modification when grown on the three strains described here, following which a few particles ( c . 1 in 5 x lo4) were able to lyse cells lysogenically infected with phage 8426. These virulent phage particles were maintained by propagation on lysogenic host cells but they reverted to the normal 8426 phage when grown on the non-lysogenic indicator. Finally phage 8426 showed another modification of its host range when grown on one of the three strains, this change was reversed when the modified phage was propagated on its normal host Staphylococcus aureus NCTC 8354.