Abstract
Summary: We have investigated a group of bacteriocinogenic strains used in the epidemiological investigation of Klebsiella infections. Transfer of plasmids from these strains to laboratory trains allowed the identification of three klebicins which use the cloacin DF13 receptor in Klebsiella but are of three distinct immunity types. These klebicins use the ferric-aerobactin determined by ColV-K30 in Escherichia coli, which is also used by cloacin DF13. We propose to call them group A klebicins, of immunity types A1, A2 and A3. On the basis of ammunity, cloacin DF13 also belongs to the klebicin A1 group.