WGS-Based Phenotyping and Molecular Characterization of the Resistome, Virulome and Plasmid Replicons in Isolates from Powdered Milk Produced in Germany.

The emergence of () in German healthcare is worrying. It is not well-investigated in the veterinary world and food chains. In the current study, antibiotic susceptibility profiles of 24 strains isolated from powdered milk samples produced in Germany were investigated by a microdilution test. Next-generation sequencing (NGS) was applied to identify genomic determinants for antimicrobial resistance (AMR), virulence-associated genes and plasmids replicons. All isolates were susceptible to the majority (14/18) of tested antibiotics. Resistance to colistin, fosfomycin, chloramphenicol and piperacillin was found. The ambler class A ß-lactamase, variants were identified in all isolates, of which was most prevalent and found in 50% of isolates. Single-nucleotide-variants of A and B conferring resistance to phenicol/quinolone were found in all isolates, and the B17 was the most prevalent found in 46% of isolates. 67% of isolates harbored A genes; however, only one was fosfomycin-resistant. Two isolates harbored genes conferring resistance to colistin, despite being susceptible. The majority of identified virulome genes were iron uptake siderophores. Two enterobactins (B, C), six adherence-related genes belonging to common pilus (ECP) and one secretion system (A gene) were found in all isolates. In contrast, yersiniabactin was found in two isolates. One ST23 strain was susceptible to all tested antibiotics, and harbored determinants discriminatory for hypervirulent strains, e.g., aerobactin, salmochelin, yersiniabactin, enterobactin and regulator of mucoid phenotype A genes that are highly associated with hypervirulent . The IncF plasmid family was found in all strains, while almost half of the isolates harbored Col440I-type plasmids and nine isolates harbored various Inc-type plasmids. The presence of carrying different resistomes and major virulent specific virulomes in powdered milk samples is alarming. This could threaten public health, particularly of neonates and infants consuming dried milk.