Potential Transfer of Antimicrobial Resistance and Zoonotic Bacteria Through Global Ornamental Fish Trade

There is an impressive global trade in live tropical freshwater ornamental fish. These consignments may contain potentiallyharmful bacteria and contaminants of therapeutics, a potential public health risk when professionals have direct contact with fish and transport water. In 2014–2015 we sampled and tested fifty consignments from 13 countries outside Europe at arrival in the Netherlands. Potential zoonotic bacteria were detected in 11 of 50 ornamental fish consignments. Aeromonasspp. (n = 59) isolated from fish showed resistance to oxytetracycline (85 % of strains), flumequine (53 %), trimethoprim-sulphamethoxazole (30 %), neomycin (34 %), florfenicol (9 %), and to nitrofurantoin (17 %). Isolates from fish consignments from Singapore and Congo showed multi-resistance against various antibiotics. In total 11 Escherichia coliisolates suspected of ESBL (extended-spectrum beta-lactamase)-production were found in 2 of 50 freshwater ornamental fish and 9 of 50 transport water samples, from Singapore (4×), Indonesia (2×), Congo (2×), Thailand (1×), and Hong Kong Special Administrative Region ofthe People's Republic of China (HKSAR) (1×). OXA-48-like carbapenemase gene variants of limited public health riskwere frequently found in Shewanella spp. Forty-nine of fifty water samples contained residues of one or more antibiotics, mostly tetracyclines and fluoroquinolones, but also chloramphenicol and nitrofurans, and of malachite green. Our findings are of concern since the current EU border inspections for import control do not consider these human health risks. It is therefore recommended to regularly screen consignments from more countries for the presence of antimicrobial resistant bacteria, residues of antibiotics, and potential zoonotic bacteria.