Group JK diphtheroid bacteremia. The successive isolation of an antibiotic-susceptible and an antigenically different multi-resistant strain.

A 71-year-old man with a permanent, subcutaneously implanted, intra-cardial pacemaker suffered from prolonged bacteremia with an antibiotic-susceptible group JK diphtheroid rod. He died in spite of the formation of specific serum antibody and parenteral treatment with ampicillin, cephradine and gentamicin. A second multi-resistant, but otherwise similar group JK strain was isolated post-mortem from the aseptically removed pacemaker electrode tip. The susceptible and the multi-resistant strains differed antigenically in crossed immunoelectrophoresis assays, and fatty acid isomer patterns were dissimilar. The theory that a multi-resistant group JK clone emerged by simple mutation in susceptible, indigenous group JK skin flora is rejected. The concept of major structural differences among group JK bacteria, possibly affecting cell-wall permeability, is supported. Crossed immunoelectrophoresis is suggested as a means for strain comparison in epidemiological surveys. Vancomycin is regarded as the antibiotic of choice for the treatment of potentially fatal, deep-seated infections.