The Influence of Bacteriophage on Streptococcus pyogenes

Abstract

SUMMARY: By the selective action of certain bacteriophages on cultures of susceptible streptococci it is possible to alter or enhance certain of their characteristics. The extractable M antigen may be greatly increased ; non-mucoid strains may become completely mucoid with or without the increase in M antigen. Some phageselected cultures have shown a marked increase in mouse virulence and some an ability to survive in normal human blood not possessed by the parent strain.Despite the great amount of work published on bacteriophages, the only extensive studies on those active against group A haemolytic streptococci are those by Evans (e.g. 1933Evans (e.g. , 1934Evans (e.g. , 1940 and Evans & Sockrider (1942). In preliminary work with phages obtained from sewage and sent to us by Professor Boulgakov of Paris, it was found that lysis was often much more readily obtained when the test was carried out in the presence of hyaluronidase (Maxted, 1952). It was also noted that the colonies of the secondary growth that appeared after vigorous lysis had taken place were often very mucoid when plated on to glucose serum agar, even when the parent strain had never shown mucoid variants upon preliminary plating. The secondary growth from one strain also showed increased M antigen content, and an ability to survive in human blood not possessed by the parent strain. A more detailed investigation was therefore made of the changes in antigenic structure, colonial appearance and virulence that are produced in cultures by passage through phage-containing media. MATERIAL AND METHODS Preparation of hyaluronidase.Minced bull testicle was extracted overnight in the cold with ~/ 1 acetic acid, neutralized, and the supernatant fluid Seitzfiltered.Source and propagation of phages. The phages used were derived from those isolated by Professor Boulgakov from Paris sewage; they were propagated in nutrient broth containing hyaluronidase, each on its particular strain of streptococcus. The phages are designated A l , As, A12 and A25. The letter indicates the Lancefield group to which the propagating strain belongs and the number the type. The phages are not specific for their propagating type strain.For the phage passage experiments with types 3 and 27 the phage A1 was adapted to these strains; for the experiments with the type 5 strain phage A6 was similarly adapted. A mixture of all four of the original phages was used for the serial transfers of strain 1506 type 30.

The Active Agent in Nascent Phage Lysis of Streptococci

“…This agent is capable of lysing live or chloroform-killed suspensions of streptococci of groups A, C and E, and it seems likely that the agent is responsible for the nascent lysis observed by Evans on streptococci belonging to these groups. Virulent phages active against group A streptococci and used in previous work (Maxted, 1955) also gave nascent lysis of otherwise resistant members of group A; such phage propagations also yielded a lytic principle similar to the one described here, although so far they have always been much less potent. This would agree with the observations of Evans that phage B563 was by far the most active of her phages in respect of nascent lysis.…”

Why Have Group A Streptococci Remained Susceptible to Penicillin? Report on a Symposium

“…Since many of the group A streptococcal tance does not develop uniformly in all microbial species. Conbacteriophages were isolated originally from sewage [25,26], tinued susceptibility of Treponema pallidum to penicillin the recent observation of penicillin-resistant enterococci raises indicates that resistance may not invariably occur despite powthe question of whether these organisms might provide the erful selective pressures that would favor its emergence. There vehicle by which phage transfer of penicillin resistance to group is, however, a time factor to be considered.…”

Surface proteins in the transduction of groups A and G streptococci

“…Some of these differences reported by various authors may be attributable to the use of living or heat-killed cells, to the media employed, to differences in the smoothness of M + and M-lawns, to use of paired and unpaired variants, or to other variables. Our findings and those of Maxted (1955) suggest that continued exposure of viable streptococci to relatively large amounts of trypsin may be an important factor for optimal demonstration of differences between M + and M -variants, as trypsin-treated living cells may rapidly regenerate M protein (Fox and Krampitz, 1956). …”

“…On the other hand, Cleary and Johnson (1977) showed that heat-killed cells of mutants producing large amounts of M protein adsorbed phage poorly, a finding that was reversed by trypsin treatment. In studies of a pair of M + and Mvariants (Maxted, 1955) lawns of M +variants were more resistant to phage infection than lawns of the M -variants. When Maxted grew these variants in broth containing trypsin and repeated the phage titration on trypsin-containing plates, he found no difference in the titres obtained with the M + and the M -variants.…”