Ascending reinfection. Uropathogens originate from the rectal flora and colonize the periurethral area leading to ascension through the urethra into the bladder.
Note. From “Pathogenic Escherichia coli” by J.B. Kaper, J.P. Nataro, and H.L. Mobley, 2004. Nat Rev Microbiol, 2, p. 123–40. Copyright 2004. Nature Publishing Group. Reprinted with permission.