A New Property of Phage Group II Staphylococcus aureus Strains: Host Restriction of Phage K14

Abstract

SUMMARYVarious strains of Staphylococcus aureus which type exclusively with phages of lytic group I1 were found to modify phage Kia so that its ability to form plaques on host KIN was lessened. The restricted phage formed plaques with high efficiency on all strains of lytic group 11. In general, it plated at lower titres on strains of lytic groups I, 111, IVY and on some strains of miscellaneous typing characteristics ; however, there were some variations among separate cultures of the same strains. For example, the restricted phage plated at high titre on strains 52~/79", 73, and PA, but formed significantly fewer numbers of plaques on strain 5 2~/ 7 9~ and on a second culture of 4 4~. Strain KIN was found to dissociate into apt (KIHI) and non-apt (mm) forms. The probability of plaque development by restricted phage on strain KIN was dependent upon the nutritional state of the cocci and also upon the proportion of apt and non-apt cells. The restriction of phage Kia was eliminated during its propagation on all strains other than lytic group 11. The unrestricted progeny particles tended to assay at equal titre on all the indicator strains. In all cases the genotype of the phage-susceptibility to host-control-remained unchanged. The observations add to existing data which indicate that strains of phage group I1 form a genetically distinct group. The suggestion is made that this phenomenon might help in taxonomic classification of strains of S . aureus.

Studies on Recently Isolated Cultures of Methicillin-resistant Staphylococcus aureus

“…These enzymes can be inactivated by heating; hence the spectrum of lysis of phage group I1 staphylococci by typing phages increases after heating (Asheshov & Jevons, 1963 ;Ralston & Baer, 1964;Stobberingh & Winkler, 1976). A further type of phage 'immunity' is the failure of typing phage 187 to adsorb to the great majority of staphylococcal strains (Odeing, 1974).…”

Construction of a chromosome map for the phage group II Staphylococcus aureus Ps55

“…With the exception of the work done by Ralston and Baer on the modification of the host range of staphylococcal phage K 14 (32,33), no DNA had been successfully transferred between S. aureus strains belonging to different phage groups due to restriction-modification barriers. The phage group II S. aureus strains in particular have always been somewhat enigmatic since they seem unable to undergo genetic exchange with other strains.…”

“…Smith and Condemine (36) stated that "technology needs to be developed to simplify map construction by using maps that already exist for related organisms." This project outlines one such technology that was applied to Staphylococcus aureus.The species is divided into five phage groups on the basis of typing patterns produced on infection with staphylococcal phages (23,32,33,42,45,48). A detailed genetic and physical map has been established in the phage group III S. aureus NCTC 8325 by using methods of classical genetics and pulsedfield gel electrophoresis (PFGE) analysis (27,28,31).…”

Biological characteristics of a type I restriction-modification system in Staphylococcus aureus

“…Restriction of lytic phage in S. aureus has been extensively studied (13,19,22). Patterns of infection of S. aureus strains with phages of the International Phage Typing system depend on R-M systems and lysogeny (27).…”