[Studies on haemolysins of "enterobacteriaceae" (author's transl)]

Haemolysin production of 1,103 strains of Enterobacteriaceae was investigated on trypticase soja agar containing washed horse erythrocytes. Nearly all haemolytic strains belonged to the genus Escherichia (103 haemolytic strains out of 349 examined). The 3 remaining haemolytic strains belonged to the genus Serratia (of which 244 strains were examined). Plasmidic determinism of haemolysis was demonstrated for six of the Hly+ E. coli strains, and these plasmids were transferred to E. coli K12, Salmonella typhia and S. typhi-murium. Investigations about coexistence of four of these plasmids with "metabolic" plasmids and with representatives of the plasmids compatibility groups presently known, showed that two of these plasmids were fi+ and belonged to the FIII group, and that two other were fi- and related to the I2 group. Thus, different plasmids can determine haemolysin-production in E. coli strains.