Bacteriophages of group A streptococci.

Bacteriophage-host relationships in the group A streptococcal system were investigated. Appropriate conditions for phage induction, propagation, and storage were studied. A set of sensitive streptococcal strains was established for lysogeny screening. The morphology of the temperate and virulent phages of group A streptococci was studied by electron microscopy and compared with that of the phages of group C streptococci. Computer image processing of the electron photomicrographs revealed subunit structures not otherwise evident. The lytic phage cycle including phage attachment to streptococci, intracellular development, and phage release was followed by electron microscopy. Observations were made on alterations in biological activity of phages due to host-induced modifications. A defective phage was identified by biological and electron microscopic techniques. The role of streptococcal phages in transduction was studied using antibiotic resistance as a marker. Some of the factors of importance to transduction of streptomycin resistance were examined in detail