Occurrence and properties of hly-plasmids in E. coli from patients of the Berne area.

1818 E. coli wild-type strains from patients of the region of Berne were screened for their haemolytic property and for carriage of hly-plasmids. Among 885 strains of fecal and 993 strains of urinary tract isolates 136 (15%) and 259 (28%) were haemolytic respectively. In five fecal, but none of the urinary strains the haemolytic activity was encoded by transmissible plasmids. In spite of independent origin, the five isolated hly-plasmids proved to be very similar. They all showed a high transfer-frequency according to their derepressed state and coded for F-sexpili. Four belonged to the rare F VI- and one to the F IV-incompatibility group. Restriction patterns after Eco R1- and Hind III-digestion were identical in three and similar in the other two plasmids. Comparing the plasmids from Berne with hly-plasmids isolated in Essex, similarities as well as specific differences were detected.