Enterococcus faecium TIR-Domain Genes Are Part of a Gene Cluster Which Promotes Bacterial Survival in Blood

Theresa M. Wagner, Jessin Janice, Fernanda L. Paganelli, Rob J. Willems, Fatemeh Askarian, Torunn Pedersen, Janetta Top, Carla De Haas, Jos A. Van Strijp, Mona Johannessen, Kristin Hegstad*

*Corresponding author for this work

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Enterococcus faecium has undergone a transition to a multidrug-resistant nosocomial pathogen. The population structure of E. faecium is characterized by a sharp distinction of clades, where the hospital-adapted lineage is primarily responsible for bacteremia. So far, factors that were identified in hospital-adapted strains and that promoted pathogenesis of nosocomial E. faecium mainly play a role in adherence and biofilm production, while less is known about factors contributing to survival in blood. This study identified a gene cluster, which includes genes encoding bacterial Toll/interleukin-1 receptor-(TIR-) domain-containing proteins (TirEs). The cluster was found to be unique to nosocomial strains and to be located on a putative mobile genetic element of phage origin. The three genes within the cluster appeared to be expressed as an operon. Expression was detected in bacterial culture media and in the presence of human blood. TirEs are released into the bacterial supernatant, and TirE2 is associated with membrane vesicles. Furthermore, the tirE-gene cluster promotes bacterial proliferation in human blood, indicating that TirE may contribute to the pathogenesis of bacteremia.

Original languageEnglish
Article number1435820
JournalInternational Journal of Microbiology
Publication statusPublished - 1 Jan 2018


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