Abstract
Fifty-fourS. sonnei colicin types and 92 indicator strains used for their determination are listed. Most of the indicators were prepared by conjugational transfer of Col factors from shigellae to the recipient strains ofE. coli K13 HfrRnal r andE. coli K12 ROW or by selection of resistant mutants of these strains or by combination of both methods. Ten indicators areS. sonnei strains. The indicator strains are suitable forE. coli colicin typing.