Expression of two distinct types of pili by a hospital-acquired Enterococcus faecium isolate

Microbiology (Reading). 2008 Oct;154(Pt 10):3212-3223. doi: 10.1099/mic.0.2008/020891-0.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Adhesion
  • Bacterial Proteins / genetics*
  • Cross Infection / microbiology
  • DNA, Bacterial / genetics
  • Enterococcus faecium / genetics*
  • Enterococcus faecium / growth & development
  • Enterococcus faecium / ultrastructure
  • Fimbriae Proteins / genetics*
  • Fimbriae, Bacterial / genetics
  • Fimbriae, Bacterial / ultrastructure*
  • Gene Expression Regulation, Bacterial
  • Genes, Bacterial
  • Genome, Bacterial
  • Gram-Positive Bacterial Infections / microbiology
  • Humans
  • Microscopy, Electron, Transmission
  • Molecular Sequence Data
  • Multigene Family
  • Oxidoreductases / genetics*
  • RNA, Messenger / genetics
  • Reverse Transcriptase Polymerase Chain Reaction
  • Temperature


  • Bacterial Proteins
  • DNA, Bacterial
  • RNA, Messenger
  • Fimbriae Proteins
  • Oxidoreductases
  • pilB protein, Bacteria

Associated data

  • GENBANK/EU909696
  • GENBANK/EU909697