Plasmid profiling as an epidemiological marker within Aeromonas salmonicida

Abstract

A collect~on of 124 isolates of Aeromonas salmonicida ssp. salmonicida from Denmark, Norway, Scotland, and North America was plasmid profiled. All stralns contained at least 1 large plas-mid in the range of 60 to 150 kb, and all stralns possessed 2 low-molecular-weight plasmids of 5.2 a n d 5.4 k b Two a d d ~ t ~ o n a l low-molecular-weight plasmlds of 5.6 and 6.4 kb were frequently encountered. A total of 23 different plasrnids were demonstrated, 12 of them being found In more than one country. Forty d~fferent plasmld profiles were detected. Seven profiles, representing 75 strains (60 %), were demonstrated in lsolates from more than one country. One profile, w ~ t h 5 plasmlds of 150, 6.4, 5.6, 5.4, and 5 2 kb, proved to be the most common one among strains from North Amerlca (25 'X), Denmark (33 "%J, and Norway (50 ':h), but ~t proved to be only the third most common one among Scott~sh strains (10 'Z,). Plasmid profiling as an epidemiological t y p ~ n g method for Aeromonds salmonlclda ssp. salmo-nlcida was evaluated. The numerical index of discriminatory power (D) was calculated, resulting In a relat~vely high D value of 0.88. However, the results of the present study suggest that plasmid profiling may be of llmited value as an epidemiological marker within Aeromonas salrnonicida ssp. salrnonicida.