The pathogenicity of Aeromonas strains relative to genospecies and phenospecies identification

The relative pathogenicity of 80 Aeromonas strains typed by biochemical (phenospecies) and genetic (genospecies) methods was assessed by determining the 50% lethal dose for each isolate in Swiss-Webster mice by intraperitoneal injection. Overall, the maximum difference in virulence potential observed between the least and most pathogenic strains was a four log (10,000-fold) difference. Results according to phenospecies designation supported previous investigations indicating that both A. hydrophila and A. sobria are inherently more pathogenic for mice than A. caviae. According to genospecies designation, the relative virulence of individual groups in decreasing order was as follows: HG 9 (A. jandaei) greater than HG 1 (A. hydrophila) and HG 12 (A. schubertii) greater than HG 10 (A. veronii biotype veronii) greater than HG 8 (A. veronii biotype sobria) greater than HG 11 (unnamed) greater than HG 2 (unnamed) greater than HG 3 (A. salmonicida), HG 4 (A. caviae) and HG 6 (A. eucrenophila) greater than HG 5 (A. media) greater than HG 7 (A. sobria).