ASSESSMENT OF DISC DIFFUSION METHODS FOR SUSCEPTIBILITY TESTING OF AEROMONAS-SALMONICIDA

In this study 5 different media were inoculated using two standard techniques (plate flooding and streaking) to determine the most appropriate medium and technique for susceptibility testing of Aeromonas salmonicida isolates. A single multidisk containing 8 compounds relevant to aquaculture was placed on each plate and, after incubation, zone sizes of inhibition were measured and compared using a one-way analysis of variance. Consistent results were obtained for each agar type and within each inoculation technique, although a statistically significant difference in zone size between media was frequently recorded. Mueller-Hinton agar supported growth and proliferation of all the A. salmonicida isolates tested, including the most fastidious, and consistently gave clear, well-defined zones of inhibition.