Discrimination between multiply-resistant klebsiella strains during a hospital outbreak: use of klebecin-typing and a screening test for plasmids.

During an outbreak of hospital infection, 71 multiply-resistant klebsiella strains were classified by two extra tests in addition to biotyping, serotyping and sensitivity testing. These were klebecin sensitivity tests (Edmondson & Cooke, 1979) and screening for plasmid DNA molecules by agarose gel electrophoresis of single colony lysates (Eckhardt, 1978). There were 56 examples of an epidemic strain of serotype K21; ten of these differed from 46 identical strains in some minor character. The other 15, although resembling the epidemic strain in biotype and antibiotic resistance differed from it sufficiently to be considered as unrelated.