Publication Abstract

The minimal inhibitory concentrations (MICs) of ten antimicrobial agents against Vibrio parahaemolyticus were determined using standardised broth microdilution protocols. Eight laboratories performed tests with incubation at 35 ℃ for 16 – 20 hours, and 7 of them also performed tests on the same isolates with incubation at 28 ℃ for 24 – 28 hours. After excluding data from individual laboratories that were excessively imprecise, the resultant data sets were analysed by the ECOFFinder and normalised resistance interpretation algorithms. In this work, the epidemiological cut-off values (CO_WT) calculated by both algorithms were identical. The CO_WT values calculated for ceftazidime, florfenicol and trimethoprim/sulfamethoxazole, 1 µg/mL, 1 µg/mL and 0.25/4.75 µg/mL, respectively, were the same when calculated from data obtained at both temperatures. The CO_WT values calculated from data obtained at 35℃ and from data obtained at 28℃ were 0.25 µg/mL and 0.5 µg/mL for enrofloxacin,  2 µg/mL and  4 µg/mL for gentamicin, 0.5 µg/mL and 1 µg/mL for oxolinic acid and 2 µg/mL and 1 µg/mL, for oxytetracycline.

The influence of the incubation temperature on the MICs obtained was investigated by comparing MICs obtained at 35 ℃ and 28 ℃ for a specific antimicrobial agent with a particular isolate by an individual laboratory. Examination of the differences between 1,473 of these paired MIC values revealed that 56% of the MIC values were identical while 38% differed from one another by not more than one dilution step. 

Peter Smith¹, Andrew Joseph^2,3, Craig Baker‐Austin^2,3, Nisha Kang^2,3, Sandrine Baron⁴, Laetitia Ledevendec⁴, 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 Jaeckel⁹, Charles M. Gieseker¹⁰, Tina C. Crosby¹⁰, Elliott C. Kittel¹⁰, Ron A. Miller¹⁰, Michelle Fuller¹⁰, Trevor Alexander¹⁰, Kayleigh Carranza¹¹, Claire B. Burbick¹¹, Biyun Ching¹², Jun Heng Soh¹², You Rong Chng¹², Wai Kwan Wong¹², Charlene J. Fernandez¹², Siow Foong Chang¹², David Verner-Jeffreys¹³, Andy Powell^2,3 .

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