July 19, 2019  |  

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

Authors: Beatson, Scott A and Ben Zakour, Nouri L and Totsika, Makrina and Forde, Brian M and Watts, Rebecca E and Mabbett, Amanda N and Szubert, Jan M and Sarkar, Sohinee and Phan, Minh-Duy and Peters, Kate M and Petty, Nicola K and Alikhan, Nabil-Fareed and Sullivan, Mitchell J and Gawthorne, Jayde A and Stanton-Cook, Mitchell and Nhu, Nguyen Thi Khanh and Chong, Teik Min and Yin, Wai-Fong and Chan, Kok-Gan and Hancock, Viktoria and Ussery, David W and Ulett, Glen C and Schembri, Mark A

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. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Journal: Infection and immunity
DOI: 10.1128/IAI.02810-14
Year: 2015

Read publication

Talk with an expert

If you have a question, need to check the status of an order, or are interested in purchasing an instrument, we're here to help.