A method for typing Listeria monocytogenes strains by classification of listeriocins and phage receptors.

A method for typing Listeria monocytogenes (L.m.) strains was developed which is based on two different approaches.

[Significance of plasmid virulence factors for transmission of nosocomial infection].

The genetical basis of germ change especially for the gain of the resistance, and virulence plasmids have been treated not only with regard to clinical consequences but also have been classified in their evolutionary importance. Mechanisms of virulence have been illustrated on example of origin of siderophors, the increase of virulence through cytotoxical damage, on the obtained ability of adhesion and colonisation as well as by enhancement of equipment with enzyms. The patient with reduced resistance has been put out as selection condition.

Haemolytic activity and characteristics of plasmid and chromosomally borne hly genes isolated from E. coli of different origin.

20 hly plasmids of different origin and source and 8 recombinant plasmids containing either chromosomally or plasmid encoded hly determinants were characterized with emphasis on their haemolytic activity. Remarkable differences among the hly genes tested were found in their haemolytic activity and in the regulation of the haemolytic activity by the extracellular iron concentration. Under iron-limiting growth conditions the haemolysin secretion encoded by 6 hly plasmids, but not by the remaining 14 hly plasmids and the chromosomal hly genes, was significantly induced.

The chromosomal fur gene regulates the extracellular haemolytic activity encoded by certain hly plasmids.

The haemolytic activity encoded by thirteen hly-plasmids of different origin and sources was examined as a function of the Fe3+-concentration in E. coli fur+ and E. coli fur- strains, respectively.