[Isolation and characterization of "Listeria monocytogenes" bacteriophages (author's transl)].

Fifteen L. monocytogenes phages are isolated from lysogenic strains without induction and are selected for phage-typing. Four of these phages are produced by strains belonging to serotype 1/2a and 1/2b, eight by strains 4b and three other phages respectively by strains 4ab, 4g and 3c. Electron micrographs of 5 of these phages show isometric heads with non contractile tails. They belong to morphological group B of Bradley. Rabbits are immunized with 7 bacteriophages and all the phages are studied by neutralization tests with these 7 antisera. This study seems complex nevertheless it is possible to distinguish four antigenic groups: A, B, C, and D. The lytic spectrum of each phage is usually restricted to strains of the serotype from which that phage is obtained. It appears that a good correlation exists between phage sensitivity and serological type of the strains. With this first set of fifteen phages, 159 of 214 (74,3%) strains of L. monocytogenes can be classified in more than 21 types but it appears that some new phages obtained from strains of serotype 1/2 must be isolated in the future. Our data indicate that these phages can be used as a phage-typing scheme for L. monocytogenes.