Conflict of interest: None declared.
Authors’ contributions: EB and BC developed the surveillance system and reporting protocol. GS, JB, EB, CA, NB and BC initiated and developed the initial outline of the manuscript. GS performed the analysis. GS, BC, JB, NB, CA, EB wrote the first draft of the manuscript. JF, PJ, DP, JP, RP, SO contributed extensively to additional versions of the manuscript. MD, CC, VE, AG, AB, PS, MJSM, ANR, YVD, RoM, MBr, MBe, SBu, JS, LF, ALe, CS, AM, DLB, BC, SBS, SBe, SvdW, MV, BL, FR, EN, IC, ALa, MSC, FP, RiM, CM, MVR, NB, LS, SJ, KTW, MP were involved in national clinical, microbiological and public health investigations as well as data collection and reporting. All authors provided input to the outline, multiple versions of the manuscript and gave approval to the final draft.