title: Expression of two distinct types of pili by a hospital-acquired Enterococcus faecium isolate.
abstract: Surface filamentous structures designated pili, and implicated in virulence, have been found on the surfaces of several Gram-positive pathogens. This work describes the conditional expression of two phenotypically distinct pilus-like structures, designated PilA and PilB, on the surface of a hospital-adapted Enterococcus faecium bloodstream isolate. E. faecium is an emerging Gram-positive opportunistic pathogen that can cause severe disease, particularly in immunocompromised patients. Expression of PilA- and PilB-type pili was analysed during different phases of growth in broth culture. During growth, PilA and PilB pilin subunits were expressed around the cross-wall in early-exponential-phase cells. Polymerization and migration of short PilB-type pili towards the poles occurred in cells from the exponential phase and long polymerized pili were expressed at the poles of cells grown to stationary phase. In contrast, PilA-type pili were not expressed in broth culture, but only when cells were grown on solid media. Furthermore, surface expression of the PilA- and PilB-type pili was regulated in a temperature-dependent manner, as polymerization of two distinct types of pili at the surface only occurred when cells were grown at 37 degrees C; no pili were observed on cells grown at 21 degrees C. Hospital-aquired E. faecium isolates were specifically enriched in pilin gene clusters, suggesting that conditional expression of pili may contribute to E. faecium pathogenesis.
authors.affiliation: Department of Medical Microbiology, University Medical Center Utrecht, Heidelberglaan 100, Rm G04.614, 3584 CX, Utrecht, The Netherlands.
authors.forename: Antoni P A
authors.initials: APA
authors.lastname: Hendrickx
authors.affiliation: Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Heidelberglaan 100, Rm G04.614, 3584 CX, Utrecht, The Netherlands.|Department of Medical Microbiology, University Medical Center Utrecht, Heidelberglaan 100, Rm G04.614, 3584 CX, Utrecht, The Netherlands.
authors.forename: Marc J M
authors.initials: MJM
authors.lastname: Bonten
authors.affiliation: Department of Medical Microbiology, University Medical Center Utrecht, Heidelberglaan 100, Rm G04.614, 3584 CX, Utrecht, The Netherlands.
authors.forename: Miranda
authors.initials: M
authors.lastname: van Luit-Asbroek
authors.affiliation: Department of Medical Microbiology, University Medical Center Utrecht, Heidelberglaan 100, Rm G04.614, 3584 CX, Utrecht, The Netherlands.
authors.forename: Claudia M E
authors.initials: CME
authors.lastname: Schapendonk
authors.affiliation: Department of Medical Microbiology, University Medical Center Utrecht, Heidelberglaan 100, Rm G04.614, 3584 CX, Utrecht, The Netherlands.
authors.forename: Angela H M
authors.initials: AHM
authors.lastname: Kragten
authors.affiliation: Department of Medical Microbiology, University Medical Center Utrecht, Heidelberglaan 100, Rm G04.614, 3584 CX, Utrecht, The Netherlands.
authors.forename: Rob J L
authors.initials: RJL
authors.lastname: Willems
mesh_terms: D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000235:genetics*; D003428:Cross Infection / Q000382:microbiology; D004269:DNA, Bacterial / Q000235:genetics; D016984:Enterococcus faecium / Q000235:genetics* / Q000254:growth & development / Q000648:ultrastructure; D036781:Fimbriae Proteins / Q000235:genetics*; D010861:Fimbriae, Bacterial / Q000235:genetics / Q000648:ultrastructure*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D016680:Genome, Bacterial; D016908:Gram-Positive Bacterial Infections / Q000382:microbiology; D006801:Humans; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D005810:Multigene Family; D010088:Oxidoreductases / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013696:Temperature
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D012333:RNA, Messenger; D036781:Fimbriae Proteins; D010088:Oxidoreductases; C068255:pilB protein, Bacteria