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Diseases of Aquatic Organisms

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DAO 155:35-42 (2023)  -  DOI:

Setting epidemiological cut-off values for Vibrio harveyi relevant to MIC data generated by a standardised microdilution method

Peter Smith1,*, Luana Cortinovis2, Tobia Pretto2, Amedeo Manfrin2, Daniela Florio3, Marialetizia Fioravanti3, Sandrine Baron4, Laëtita Le Devendec4, Eric Jouy4, Alain Le Breton5, Sara Picon-Camacho5, Ivana Giovanna Zupičić6, Dražen Oraić6, Snježana Zrnčić6

1Department of Microbiology, University of Galway, Galway H91 TK33, Ireland
2Fish Pathology Unit, Istituto Zooprofilattico Sperimentale delle Venezie, 35020 Legnaro, Italy
3Department of Veterinary Medical Sciences, Alma Mater Studiorum Università di Bologna, 40064 Ozzano Emilia (BO), Italy
4Anses, Ploufragan-Plouzané-Niort Laboratory, Mycoplasmology-Bacteriology and Antimicrobial Resistance Unit, 22440 Ploufragan, France
5Vet’eau-Selarl du Dr Alain Le Breton, 1989 Rue des Pyrénées, 31330 Grenade sur Garonne, France
6Laboratory for Fish and Molluscs Diseases, Croatian Veterinary Institute, 10000 Zagreb, Croatia
*Corresponding author:

ABSTRACT: The lack of internationally harmonised criteria for interpreting the data generated by standardised susceptibility testing methods presents a serious obstacle for the development of prudent use of antimicrobials in aquaculture. The data required to set epidemiological cut-off values for minimum inhibitory concentrations for antibiotic agents against Vibrio harveyi was determined using a standard microdilution method that specified the use of cation-adjusted Mueller Hinton broth and incubation at 28°C for 24 to 28 h. In total, 120 observations were made in 4 independent laboratories from 109 unique isolates. The aggregated data from these laboratories were analysed by the normalised resistance method and by ECOFFinder to calculate epidemiological cut-off values. The data for chloramphenicol, meropenem and sulfamethoxazole were not considered as suitable for analysis. The data for ampicillin indicated that this species is innately resistant to this agent. No acceptable ranges for quality control strains have been set for ceftazidime and, therefore, only provisional cut-off values could be generated for this agent. The epidemiological cut-off values were, however, calculated for the other 6 agents. These values were ≤0.5 µg ml-1 for enrofloxacin, ≤1 µg ml-1 for florfenicol, oxolinic acid and oxytetracycline, ≤4 µg ml-1 for gentamicin and ≤0.5/9.5 µg ml-1 for trimethoprim/sulfamethoxazole. Evidence is presented demonstrating that the data for these 6 antimicrobial agents was of sufficient quantity and quality that they could be used by the relevant authorities to set internationally harmonised, consensus epidemiological cut-off values for V. harveyi.

KEY WORDS: Vibrio harveyi · Standardised MIC protocol · Epidemiological cut-off value · NRI · ECOFFinder

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Cite this article as: Smith P, Cortinovis L, Pretto T, Manfrin A and others (2023) Setting epidemiological cut-off values for Vibrio harveyi relevant to MIC data generated by a standardised microdilution method. Dis Aquat Org 155:35-42.

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