Lastly, nine S. sonnei strains isolated from cases occurring in June/July 2011 acquired an IncB-O plasmid, sharing homology with the MDR plasmid pHUSEC41-1 originally identified in an older O104 : H4 enteroaggregative Shiga toxin-producing E. coli (HUSEC41), which included a type IV pilus biosynthesis cluster pilL–V identical to that found on plasmid pSERB1 (Künne et al., 2012). We further identified 11 S. sonnei strains harbouring a plasmid with homology to Salmonella enterica plasmid pSH146_65, additionally carrying a distinct type IV pilus cluster pilL–V (Han et al., 2012).