SYSTEMATIC ASSESSMENT OF GEOGRAPHICALLY AND CLINICALLY DIVERSE AEROMONADS

Numerical taxonomy was used to analyze data obtained on 167 Aeromonas strains collected from the USA, N.E. Africa, Bangladesh, India, Indone sia, and Puerto Rico. The strains included dinical, environmental, and veterinary isolates. Each strain was tested at 36-degrees-C +/- 1-deg rees-C for 80 unit characters that included morphological, biochemical , antimicrobial resistance, and virulence-associated markers. The data for 50 of these characters were analyzed by the SAS/TAXAN(R) program using Simple Matching and Jaccard coefficients. At a similarity coeffi cient of 85%, the 167 strains clustered into 12 phenons plus 13 single unclustered strains. All clusters but one contained only one DNA grou p definition strain. The major clusters resembled the three clinical s pecies Aeromonas hydrophila, Aeromonas veronii biovar sobria, and Aero monas caviae, with smaller clusters for the species Aeromonas veronii biovar veronii and Aeromonas schubertii. Additional clusters delineate d were: an ''arabinose-negative'' biovar of A. hydrophila and clusters for two newly validated species, A. jandaei and A. trota. This system atic assessment provides a comprehensive taxonomic study of a geograph ically and clinically diverse group of aeromonads and delineates, for the first time, essentially all of the currently recognized genospecie s using phenotypic clustering.