E. rhusiopathiae resistance elements

Goose erysipelas is a serious problem in waterfowl breeding in Poland. However, knowledge about the characteristics of the E. rhusiopathiae strains causing this disease is limited. In this study, the drug susceptibility and serotype of four E. rhusiopathiae strains from domestic geese was determined and their whole genomic sequences (WGS) were analyzed for the presence of resistance genes, integrative conjugative elements (ICEs) and prophage DNA. Sequence type and phylogeny were compared with 363 publicly available E. rhusiopathie strains as well as 13 strains of other Erysipelothrix species. Our strains represented serotypes 2 and 5 and the MLST group ST 4, 32 and two new STs 242 and 243 . Their assembled circular genomes ranged from 1,8 to 1,9 kbp with a GC content of 36-37%; a small plasmid was detected in strain 1023. Strains 1023 and 267 were characterized by multidrug resistance. The following resistance genes were detected in the genome of strain 1023: erm47, tetM, and lsaE-lnuB-ant(6)-Ia-spw while strain 267 contained the tetM and ermB genes. Resistance to quinolones was determined by a mutation in the gyrA gene. The tetM gene was embedded in an integrative conjugative transposon Tn916-like, which in strain 1023, together with the other resistance genes, was located on a large ICE of 130 kbp designated as ICEEr1023. A minor ICE of 74 kbp was identified in strain 1012 (ICEEr1012). Phylogenetic analysis indicated the genetic distinctiveness of strains 1023, 1012 and 267. This work deepens the knowledge about the characteristics of E. rhusiopathiae strains from geese and for the first time reveals the occurrence of erm47 and ermB resistance genes in these bacteria. Phage infection seems to be related to the transfer of the ermB gene, while ICEs probably play a key role in the spread of the other identified resistance genes in E. rhusiopathiae.