Asymptomatic bacteriuria Escherichia coli strain 83972 carries mutations in the foc locus and is unable to express F1C fimbriae

Roos, Viktoria, Schembri, Mark A., Ulett, Glen C. and Klemm, Per (2006) Asymptomatic bacteriuria Escherichia coli strain 83972 carries mutations in the foc locus and is unable to express F1C fimbriae. Microbiology, 152 Part 6: 1799-1806.


Author Roos, Viktoria
Schembri, Mark A.
Ulett, Glen C.
Klemm, Per
Title Asymptomatic bacteriuria Escherichia coli strain 83972 carries mutations in the foc locus and is unable to express F1C fimbriae
Journal name Microbiology   Check publisher's open access policy
ISSN 1350-0872
Publication date 2006
Sub-type Article (original research)
DOI 10.1099/mic.0.28711-0
Volume 152
Issue Part 6
Start page 1799
End page 1806
Total pages 8
Place of publication Reading
Publisher Society for General Microbiology
Collection year 2006
Language eng
Subject C1
320401 Medical Bacteriology
780105 Biological sciences
Abstract Escherichia coli is the most common organism associated with asymptomatic bacteriuria (ABU). In contrast to uropathogenic E. coli (UPEC), which causes symptomatic urinary tract infection (UTI), very little is known about the mechanisms by which these strains colonize the urinary tract. Bacterial adhesion conferred by specific surface-associated adhesins is normally considered as a prerequisite for colonization of the urinary tract. The prototype ABU E coli strain 83972 was originally isolated from a girl who had carried it asymptomatically for 3 years. This study characterized the molecular status of one of the primary adhesion factors known to be associated with UTI, namely F1C fimbriae, encoded by the foc gene cluster. F1C fimbriae recognize receptors present in the human kidney and bladder. Expression of the foc genes was found to be up-regulated in human urine. It was also shown that although strain 83972 contains a seemingly intact foc gene cluster, F1C fimbriae are not expressed. Sequencing and genetic complementation revealed that the focD gene, encoding a component of the F1C transport and assembly system, was non-functional, explaining the inability of strain 83972 to express this adhesin. The data imply that E. coli 83972 has lost its ability to express this important colonization factor as a result of host-driven evolution. The ancestor of the strain seems to have been a pyelonephritis strain of phylogenetic group B2. Strain 83972 therefore represents an example of bacterial adaptation from pathogenicity to commensalism through virulence factor loss.
Keyword Microbiology
Urinary-tract-infection
Virulence Properties
Type-1c Fimbriae
Fimh Genes
Sequence
Adherence
Adhesins
Strains
Antigen
Q-Index Code C1

 
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