Epidemiological Cutoff Values for Standard Broth Microdilution Susceptibility Testing of Isolated from Fishes

Authors

Charles M. Gieseker, Food and Drug Administration, Center for Veterinary Medicine, Office of Research, Laurel, Maryland, USA.
Patricia S. Gaunt, Thad Cochran National Warmwater Aquaculture Center, College of Veterinary Medicine, Mississippi State University, Stoneville, Mississippi, USA.
John P. Hawke, Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, USA.
Tina C. Crosby, Food and Drug Administration, Center for Veterinary Medicine, Office of Research, Laurel, Maryland, USA.
Nicholas R. Hasbrouck, Food and Drug Administration, Center for Veterinary Medicine, Office of Research, Laurel, Maryland, USA.
Dana X. Gao, Thad Cochran National Warmwater Aquaculture Center, College of Veterinary Medicine, Mississippi State University, Stoneville, Mississippi, USA.
Annelies M. Declercq, Department of Animal Sciences and Aquatic Ecology, Laboratory of Aquaculture and Artemia Reference Center, Ghent University, Ghent, Belgium.

Document Type

Article

Publication Date

9-1-2022

Abstract

, the causative agent of columnaris disease in a large variety of freshwater fish, is a major problem in commercial aquaculture. A limited number of antimicrobial therapies are available to control this disease; therefore, these agents must be used judiciously. To facilitate effective monitoring for changes in susceptibility, the Clinical Laboratory Standards Institute (CLSI) has a standard broth microdilution test method specific for . However, there are no CLSI-approved criteria (termed epidemiological cutoff values [ECVs]) to interpret results. Nevertheless, researchers have developed provisional ECVs based on testing by one laboratory. To satisfy CLSI data requirements, three laboratories used the standard method to generate additional antimicrobial susceptibility data against ampicillin, enrofloxacin, erythromycin, florfenicol, flumequine, gentamicin, oxolinic acid, oxytetracycline, sulfadimethoxine/ormetoprim, and sulfamethoxazole-trimethoprim using 109 isolates. The new data combined with previously published data from 120 isolates were analyzed and ECVs proposed to CLSI. Of the 10 antimicrobials, ECVs were approved for ampicillin, enrofloxacin, erythromycin, florfenicol, flumequine, oxolinic acid, and oxytetracycline, which were published in the 2020 edition of the CLSI document VET04 performance standards. These ECVs will help microbiologists categorize decreased antimicrobial susceptibility among and will help in surveillance efforts to ensure judicious antimicrobial use.

Publication Source (Journal or Book title)

Microbial drug resistance (Larchmont, N.Y.)

First Page

948

Last Page

955

Recommended Citation

Gieseker, C. M., Gaunt, P. S., Hawke, J. P., Crosby, T. C., Hasbrouck, N. R., Gao, D. X., & Declercq, A. M. (2022). Epidemiological Cutoff Values for Standard Broth Microdilution Susceptibility Testing of Isolated from Fishes. Microbial drug resistance (Larchmont, N.Y.), 28 (9), 948-955. https://doi.org/10.1089/mdr.2022.0019