Resistance patterns of Aeromonas salmonicida to common antimicrobial agents

Abstract

The antibiotic sensitivity profiles of a collection of Aeromonas salmonicida isolates obtained from a range of geographical locations in Scotland was investigated. The investigation was part of a collaborative study to characterise A. salmonicida on a range of parameters which include cytotoxicity, virulence, autoagglutination and outer membrane protein profiles. Twenty eight isolates, including A. salmonicida fcs strain and A. salmonicida 1102, were subjected to antimicrobial sensitivity testing of 11 antimicrobial agents by a disc diffusion method and an agar dilution method to determine minimum inhibitory concentrations (mic's). The semi-quantitative results of the disc test were confirmed and a more precise value obtained by the second method. Seven different sensitivity patterns were detected. All the 12 isolates which were resistant to oxolinic acid were found to be resistant to the 5 antimicrobial agents oxytetracycline, oxolinic acid, sulphamethoxazole and the potentiated-sulphonamides Romet-30 and co-trimoxazole.