[The biological properties of Salmonella enteritidis strains isolated from different sources in the period of 1969-1989].

The study of S. enteritidis cultures of different origin, isolated at the period of 1969-1989, revealed that almost all strains isolated in 1988-1989 belonged to phagovar 1 and carried a plasmid with a molecular weight of 36 MD, while of the cultures isolated in 1969-1984 only one belonged to phagovar 1 and had a plasmid of 36 MD. All S. enteritidis strains under study, irrespective of their origin and time of isolation, were highly virulent for mice, experimentally infected by different routes. S. enteritidis cultures isolated from patients exhibited higher resistance to the bactericidal action of normal guinea pig serum than strains isolated from chickens and from water. S. enteritidis mutants having lost their plasmid of 36 MD were characterized by lower virulence for mice and guinea pigs.