Molecular analysis of asymptomatic bacteriuria Escherichia coli strain VR50 reveals adaptation to the urinary tract by gene acquisition
Urinary tract infections (UTIs) are among the most common infectious diseases of humans, with Escherichia coli responsible for >80% of all cases. One extreme of UTI is asymptomatic bacteriuria (ABU), which occurs as an asymptomatic carrier state that resembles commensalism. To understand the evol...
Saved in:
Published in | Infection and immunity Vol. 83; no. 5; pp. 1749 - 1764 |
---|---|
Main Authors | , , , , , , , , , , , , , , , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
United States
American Society for Microbiology
01.05.2015
|
Subjects | |
Online Access | Get full text |
Cover
Loading…
Summary: | Urinary tract infections (UTIs) are among the most common infectious diseases of humans, with Escherichia coli responsible for >80% of all cases. One extreme of UTI is asymptomatic bacteriuria (ABU), which occurs as an asymptomatic carrier state that resembles commensalism. To understand the evolution and molecular mechanisms that underpin ABU, the genome of the ABU E. coli strain VR50 was sequenced. Analysis of the complete genome indicated that it most resembles E. coli K-12, with the addition of a 94-kb genomic island (GI-VR50-pheV), eight prophages, and multiple plasmids. GI-VR50-pheV has a mosaic structure and contains genes encoding a number of UTI-associated virulence factors, namely, Afa (afimbrial adhesin), two autotransporter proteins (Ag43 and Sat), and aerobactin. We demonstrated that the presence of this island in VR50 confers its ability to colonize the murine bladder, as a VR50 mutant with GI-VR50-pheV deleted was attenuated in a mouse model of UTI in vivo. We established that Afa is the island-encoded factor responsible for this phenotype using two independent deletion (Afa operon and AfaE adhesin) mutants. E. coli VR50afa and VR50afaE displayed significantly decreased ability to adhere to human bladder epithelial cells. In the mouse model of UTI, VR50afa and VR50afaE displayed reduced bladder colonization compared to wild-type VR50, similar to the colonization level of the GI-VR50-pheV mutant. Our study suggests that E. coli VR50 is a commensal-like strain that has acquired fitness factors that facilitate colonization of the human bladder. |
---|---|
Bibliography: | ObjectType-Case Study-2 SourceType-Scholarly Journals-1 ObjectType-Feature-4 content type line 23 ObjectType-Report-1 ObjectType-Article-3 ObjectType-Article-1 ObjectType-Feature-2 USDOE AC05-00OR22725 Citation Beatson SA, Ben Zakour NL, Totsika M, Forde BM, Watts RE, Mabbett AN, Szubert JM, Sarkar S, Phan M-D, Peters KM, Petty NK, Alikhan N-F, Sullivan MJ, Gawthorne JA, Stanton-Cook M, Nhu NTK, Chong TM, Yin W-F, Chan K-G, Hancock V, Ussery DW, Ulett GC, Schembri MA. 2015. Molecular analysis of asymptomatic bacteriuria Escherichia coli strain VR50 reveals adaptation to the urinary tract by gene acquisition. Infect Immun 83:1749–1764. doi:10.1128/IAI.02810-14. S.A.B., N.L.B.Z., and M.T. contributed equally to this article. Present address: Makrina Totsika, Institute of Health and Biomedical Innovation, School of Biomedical Sciences, Queensland University of Technology, Kelvin Grove, QLD, Australia; Rebecca E. Watts, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia; Nicola K. Petty, The Ithree Institute, University of Technology Sydney, Sydney, NSW, Australia; Viktoria Hancock, Therapeutic Fluid Research Group, Gambro Lundia AB, Lund, Sweden; David W. Ussery, Biosciences Division, Oak Ridge National Laboratories, Oak Ridge, Tennessee, USA. |
ISSN: | 0019-9567 1098-5522 |
DOI: | 10.1128/IAI.02810-14 |