Development of intracellular bacterial communities of uropathogenic Escherichia coli depends on type 1 pili

Kelly J. Wright, Patrick C. Seed, Scott J. Hultgren*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

257 Scopus citations


Uropathogenic Escherichia coli, the predominant causative agent of urinary tract infections, use type 1 pili to bind and invade bladder epithelial cells. Upon entry, the bacteria rapidly replicate and enter a complex developmental pathway ultimately forming intracellular bacterial communities (IBCs), a niche with biofilm-like properties protected from innate defences and antibiotics. Paradoxically, bacteria within IBCs produce type 1 pili, an organelle thought only to be an extracellular colonization factor. Thus, we investigated the function of type 1 pili in IBC development. The cystitis isolate, UTI89, was genetically manipulated for conditional fim expression under control of the tet promoter. In this strain, UTI89- tetR/P tet fim, piliation is constitutively inhibited by the tetracycline repressor, TetR. Repression is relieved by anhydrotetracycline (AHT) treatment. UTI89-tetR/Ptet fim and the isogenic control strain, UTI89- tetR, grown in the presence of AHT, colonized the bladder and invaded the superficial umbrella cells at similar levels at early times in a murine model of infection. However, after invasion UTI89-tetR/Ptet fim became non-piliated and was unable to form typical IBCs comprised of tightly packed, coccoid-shaped bacteria in contrast to the control strain, UTI89-tetR. Thus, this work changes the extracellular colonization functional paradigm of pili by demonstrating their intracellular role in biofilm formation.

Original languageEnglish (US)
Pages (from-to)2230-2241
Number of pages12
JournalCellular Microbiology
Issue number9
StatePublished - Sep 2007

ASJC Scopus subject areas

  • Virology
  • Microbiology
  • Immunology


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