Detection of VIM-1-Producing Enterobacter cloacae and Salmonella enterica Serovars Infantis and Goldcoast at a Breeding Pig Farm in Germany in 2017 and Their Molecular Relationship to Former VIM-1-Producing Infantis Isolates in German Livestock Production.

In 2011, VIM-1-producing serovar Infantis and were isolated for the first time in four German livestock farms. In 2015/2016, highly related isolates were identified in German pig production. This raised the issue of potential reservoirs for these isolates, the relation of their mobile genetic elements, and potential links between the different affected farms/facilities. In a piglet-producing farm suspicious for being linked to some findings in Germany, fecal and environmental samples were examined for the presence of carbapenemase-producing and spp. Newly discovered isolates were subjected to Illumina whole-genome sequencing (WGS) and S1 pulsed-field gel electrophoresis (PFGE) hybridization experiments. WGS data of these isolates were compared with those for the previously isolated VIM-1-producing Infantis isolates from pigs and poultry. Among 103 samples, one Goldcoast isolate, one Infantis isolate, and one isolate carrying the gene were detected. Comparative WGS analysis revealed that the gene was part of a particular Tn-like transposable element in all isolates. It was located on IncHI2 (ST1) plasmids of ∼290 to 300 kb with a backbone highly similar (98 to 100%) to that of reference pSE15-SA01028. SNP analysis revealed a close relationship of all VIM-1-positive Infantis isolates described since 2011. The findings of this study demonstrate that the occurrence of the gene in German livestock is restricted neither to a certain bacterial species nor to a certain serovar but is linked to a particular Tn-like transposable element located on transferable pSE15-SA01028-like IncHI2 (ST1) plasmids, being present in all of the investigated isolates from 2011 to 2017. Carbapenems are considered one of few remaining treatment options against multidrug-resistant Gram-negative pathogens in human clinical settings. The occurrence of carbapenemase-producing in livestock and food is a major public health concern. Particularly the occurrence of VIM-1-producing Infantis in livestock farms is worrisome, as this zoonotic pathogen is one of the main causes for human salmonellosis in Europe. Investigations on the epidemiology of those carbapenemase-producing isolates and associated mobile genetic elements through an in-depth molecular characterization are indispensable to understand the transmission of carbapenemase-producing along the food chain and between different populations to develop strategies to prevent their further spread.