CHARACTERIZATION OF AEROMONAS-HYDROPHILA STRAINS OF CLINICAL, ANIMAL,AND ENVIRONMENTAL ORIGIN EXPRESSING THE O-34 ANTIGEN

A collection of Aeromonas strains of different origins were characteri zed for isolates expressing the O:34 somatic antigen. Of over 200 stra ins tested, approximately 14% belonged to serogroup O:34 with >85% of these strains identified as A. hydrophila regardless of source. A subs et of 14 A. hydrophila O:34 strains were further analyzed for a number of structural and pathogenic features. Most O:34 strains expressed si milar whole-cell protein profiles with regards to minor bands, but maj or band differences were noted in outer membrane proteins (OMPs) migra ting between the 31K and 58K region, OMP profiles could be subdivided into three distinct patterns. All O:34 strains expressed a heterogeneo us O polysaccharide side chain profile in their lipopolysaccharide (LP S), although some variation in the electrophoretic migration of lower and higher molecular weight LPS bands was noted, Polyclonal antisera r aised against a 45-K OMP-associated protein of one O:34 strain (AH-195 ) reacted in immunoblot assays with a major 43 to 46-K OMP in 11 of 14 (79%) O:34 strains tested, Most O:34 strains (69%) were found to be p athogenic in mice with LD-50 values (i.p.) of <1.0 x 10(7) CFU; pathog enicity appeared to correlate best with elevated protease activity. Th e collective results suggest significant differences in both structura l and pathogenic properties between some members of the O:34 group ori ginating from human and nonhuman (fish, water) sources.