Molecular analysis of asymptomatic bacteriuria escherichia coli strain VR50 reveals adaptation to the urinary tract by gene acquisition

Beatson, Scott A., Zakour, Nouri L. Ben, Totsika, Makrina, Forde, Brian M., Watts, Rebecca E., Mabbett, Amanda N., Szubert, Jan M., Sarkar, Sohinee, Phan, Minh-Duy, Peters, Kate M., Petty, Nicola K., Alikhan, Nabil-Fareed, Sullivan, Mitchell J., Gawthorne, Jayde A., Stanton-Cook, Mitchell, Nhu, Nguyen Thi Khanh, Chong, Teik Min, Yin, Wai-Fong, Chan, Kok-Gan, Hancock, Viktoria, Ussery, David W., Ulett, Glen C., & Schembri, Mark A. (2015) Molecular analysis of asymptomatic bacteriuria escherichia coli strain VR50 reveals adaptation to the urinary tract by gene acquisition. Infection and Immunity, 83(5), pp. 1749-1764.

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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.

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ID Code: 84119
Item Type: Journal Article
Refereed: Yes
DOI: 10.1128/IAI.02810-14
ISSN: 1098-5522
Divisions: Current > Schools > School of Biomedical Sciences
Current > QUT Faculties and Divisions > Faculty of Health
Current > Institutes > Institute of Health and Biomedical Innovation
Copyright Owner: Copyright 2015 American Society for Microbiology
Deposited On: 14 May 2015 03:51
Last Modified: 21 May 2015 04:51

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