The Use of Chromogenic Media for α-Glucosidase Determination and Presumptive Drug Susceptibility Profiles in the Fish Pathogen Nocardia seriolae

Abstract

The utility of chromogenic media for determination of α-glucosidase (α-glu) activity in 116 Nocardia seriolae isolates was investigated. In all isolates, the results obtained using chromogenic media were identical to those of the API ZYM test. All the α-glu-positive isolates (n = 27) were erythromycin (Em)-sensitive, and more than half of them (n = 18) were oxytetracycline (OTC)-resistant. On the other hand, all the α-glu-negative isolates (n = 89) were OTC-sensitive, and most of them (n = 81) were Em-resistant. These results supported the relationship between the α-glu activity and drug susceptibility profiles in N. seriolae. Therefore, chromogenic media can be used as a simple and reproducible one-step test to determine the α-glu activity and presumptive drug susceptibility profiles in N. seriolae.