Gieseker, Charles M.3; Mayer, Tamara D.3; Crosby, Tina C.3; Carson, Jeremy4; Dalsgaard, Inger1; Darwish, Ahmed M.5; Gaunt, Patricia S.11; Gao, Dana X.11; Hsu, Hui-Min7; Lin, Tsang L.8; Oaks, J. Lindsay9; Pyecroft, Melissa4; Teitzel, Charlene9; Somsiri, Temdoung12; Wu, Ching C.8
1 National Veterinary Institute, Technical University of Denmark2 Section for Bacteriology, Pathology and Parasitology, National Veterinary Institute, Technical University of Denmark3 US Food and Drug Administration4 Queensland Department of Primary Industries5 United States Department of Agriculture6 Mississippi State University7 University of Wisconsin-Madison8 Purdue University9 University of Washington10 Kasetsart University11 Mississippi State University12 Kasetsart University
A multi-laboratory broth microdilution method trial was performed to standardize the specialized test conditions required for the fish pathogens Flavobacterium columnare and F. psychrophilum. Nine laboratories tested the quality control (QC) strains Escherichia coli ATCC 25922 and Aeromonas salmonicida subsp. salmonicida ATCC 33658 against 10 antimicrobials (ampicillin, enrofloxacin, erythromycin, florfenicol, flumequine, gentamicin, ormetoprim/sulfadimethoxine, oxolinic acid, oxytetracycline, and trimethoprim/sulfamethoxazole) in diluted (4 g l−1) cation-adjusted Mueller-Hinton broth incubated at 28 and 18°C for 44–48 and 92–96 h, respectively. QC ranges were set for 9 of the 10 antimicrobials. Most of the minimal inhibitory concentration (MIC) distributions (16 of 18, 9 drugs at both temperatures) for A. salmonicida ATCC 33658 were centered on a single median MIC ± 1 two-fold drug dilution resulting in a QC range that spanned 3 dilutions. More of the E. coli ATCC 25922 MIC distributions (7 of 16) were centered between 2 MIC dilutions requiring a QC range that spanned 4 dilutions. A QC range could not be determined for E. coli ATCC 25922 against 2 antimicrobials at the low temperature. These data and their associated QC ranges have been approved by the Clinical and Laboratory Standards Institute (CLSI), and will be included in the next edition of the CLSI M49-A Guideline. This method represents the first standardized reference method for testing fish pathogenic Flavobacterium spp.
Diseases of Aquatic Organisms, 2012, Vol 101, Issue 3, p. 207-215
Standard methods; Antimicrobial susceptibility testing; Fish; Flavobacteria