Escherichia hermannii: susceptibility pattern to beta-lactams and production of beta-lactamase

The susceptibility pattern of Escherichia hermannii, although closely related to Escherichia coli according to its biochemical patterns, was clearly distinguishable by its susceptibility to beta-lactams by both diffusion and dilution methods from E. coli penicillinase producing or non-producing strains, Citrobacter diversus, Klebsiella pneumoniae, and Klebsiella oxytoca. Beta-lactamase clavulanate-sensitive activity was localized with various isoelectric points from 7.0 to 8.5. No cross hybridization with DNA intragenic probes (blaTEM, blaSHV, blaCARB and blaOXY) was observed by dot blot procedure.