Publication Abstract

This work was performed to generate the data needed to set epidemiological cut-off values for inhibition zone data for eight antimicrobial agents against Vibrio parahaemolyticus determined using standardised disc diffusion protocols at 35℃ and 28℃. The zone data aggregated from 3 - 5 [FA1] [PS2] laboratories were analysed by the normalised resistance interpretation algorithm. The cut-off values calculated for ceftazidime, florfenicol and gentamicin, ≥24 mm, ≥29 mm and ≥14 mm, respectively, were the same when calculated from data obtained at both temperatures. The cut-off values calculated from data obtained at 35℃ and at 28℃ were ≥21 mm and ≥20 mm for enrofloxacin, ≥28 mm and ≥32 mm for meropenem, ≥17 mm and ≥18 mm for oxolinic acid, ≥22 mm and ≥24 mm for oxytetracycline and ≥20 mm and ≥21 mm for trimethoprim/sulfamethoxazole, respectively. The influence of the incubation temperature on inhibition zone sizes was investigated by calculating the difference between the zones obtained at 35℃ and 28℃ for a specific antimicrobial agent with a particular isolate by an individual laboratory. The mean of the differences (zone size at 35℃ minus zone size at 28℃) calculated for 1,314 paired observations was 0.38 mm with a standard deviation of 2.68 mm[SS3] [PS4] . The data generated in this work will be submitted to the Clinical and Laboratory Standards Institute and the European Committee on Antimicrobial Susceptibility Testing for consideration in their setting of internationally agreed-upon epidemiological cut-off values for V. parahaemolyticus that are essential for interpreting antimicrobial susceptibility testing data of this species.

Peter Smith¹, Andrew Joseph^2,3, Craig Baker‐Austin^2,3, Nisha Kang^2,3, Sandrine Baron⁴, Laëtitia Le Devendec⁴, Eric Jouy⁴, Thomas Chisnall⁵, Alistair R, Davies⁵, Stefan Schwarz^6,7, Andrea T. Feßler^6,7, Tanja Ahrens^6,7, Johanna Jahnen^6,7, Thomas Alter⁸, Susanne Fleischmann⁸, Jens Andre Hammerl⁹, Claudia Jäckel⁹, David Verner-Jeffreys¹⁰, Andy Powell^2,3.