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Background and objectives: Within the last couple of years it was shown that the occurrence of carbapenem resistant bacteria is no longer limited to clinical settings. Carbapenemase-producing bacteria have been isolated from environmental surroundings as well as wild birds, companion- and food-producing animals all over the world. This situation is worrying and depicts an important issue for the public health sector. In 2013, the EU legislation implemented the monitoring of carbapenem-resistance in Salmonella and E. coli in food-producing animals as well as meat samples derived thereof (2013/652/EU). However, vegetables, fruits or sea food, are frequently consumed raw and might also be a source of antimicrobial resistant bacteria. In the here described study, seafood samples derived from retail markets in Berlin, Germany (sampled from December 2015 to August 2016) were investigated for the presence of carbapenemase-producing Enterobacteriaceae.
Materials and methods: A set of 45 Enterobacteriaceae isolated from clams and shrimps were investigated for the presence of the carbapenemase genes blaVIM, blaNDM, blaOXA-48, blaKPC and blaGES using real-time PCR. Positive isolates were further investigated by MIC determination, plasmid transformation and whole genome sequencing, followed by a subsequent data analysis using the CGE platform (http://www.genomicepidemiology.org/).
Results: Out of the 45 investigated isolates, one E. coli (ST10) derived from a Venus clam - harvested in the Mediterranean Sea - contained blaVIM-1. This gene was part of the variable region of a class I integron accompanied by the resistance genes aacA4, aphA15, aadA1, catB2 as well as sul1. Whole genome analysis showed that beside the class 1 integron, several additional resistance genes including the extended-spectrum beta-lactamase blaSHV-12 and the fluoroquinolone resistance gene qnrS1 were co-located on the same IncY plasmid. In addition blaACC-1 was detected within the bacterial chromosome.
Conclusion: The presence of carbapenemase-producing Enterobacteriaceae in German retail seafood is worrisome and emphasises the importance of further monitoring programs as well as the admittance of seafood samples into the national surveillance programmes. In the same way intervention strategies including the prevention of an environmental spread of the resistant bacteria are crucial in human- as well as veterinary medicine.