Pilot study: “Antimicrobial resistance in ornamental fish”

Abstract

Summary This pilotstudy is performed to investigate the presence and characteristics of antimicrobial resistance in ornamental fish. We focused on the presence of cephalosporin and quinolone resistance. 27 Isolates, selected out of 237 strains isolated in the past five years, where identified by classical and 16SrDNA typing. Antimicrobial disk susceptibility testing was performed using oxytetracylcline, cefotaxim, oxolinic acid and ampicilin, according to the CLSI protocol. These tests where used to select samples for ESBL confirmation testing and MIC determination. These selected samples were also screened using a micro-array and for the presence of mutations in the gyrA and parC region of the QRDR and by pcr for the presence of specific PMQR’s (qnrA, qnrB, qnrC, qnrD, qnrS, qepA, and aac (6’) 1b- cr). We found point mutations in the gyrA of Aeromonas and Citrobacter at locations corresponding with data found in recent literature. We also demonstrated the presence of a qnrB in the Citrobacter freundii. Overall, we found no real ESBL’s, but found transmissible quinolone resistance genes in Citrobacter. Taken the number of samples, this study indicates a broad presence of antimicrobial resistance in ornamental fish. Therefore, it is concluded that active surveillance of resistance genes of concern for public health like ESBL’s and plasmid mediated quinolone resistance genes should be conducted routinely. Also the free purchase by the public, of antimicrobials for ornamental fish, legalized by the five gram regulation should be restricted.