Characterization of daptomycin non-susceptible Enterococcus faecium producing urinary tract infection in a renal transplant recipient

Objectives. Characterization of a urine isolate of daptomycin non-susceptible Enterococcus faecium recovered from a patient with kidney transplantation and no history of daptomycin exposure. Methods. After isolation in a urine sample, identification of E. faecium was confirmed by amplification of the E. faecium-specific gene encoding D-alanyl-D-alanine ligase (ddl) and daptomycin susceptibility testing was performed by E-test on cation-adjusted Mueller-Hinton agar. In order to determine the genetic bases of daptomycin resistance, the open reading frames of five genes previously associated with daptomycin resistance in enterococci were sequenced. Results. Substitutions in the response regulator LiaR (S19F) and cardiolipin synthase (R218Q) were identified. Conclusions. To the best of our knowledge, this is the first characterization of emerging daptomycin resistance in E. faecium in a Spanish hospital in the absence of daptomycin exposure and in a renal transplant recipient.