why do urinary tract infections recur
Urinary Tract Infections (UTIs). Urinary tract infections (UTIs) are a common type of infection caused by bacteria (most often E. coli) that travel up the urethra to the bladder. A bladder infection is called cystitis. If bacterial infection spreads to the kidneys and ureters, the condition is called pyelonephritis. (Sometimes lower UTI symptoms may be the only signs of kidney infection. 2  People at highest risk for such silent upper urinary tract infections include patients with diabetes, impaired immune systems, or a history of relapsing or recurring UTIs.). 3  An increased need to urinate at night.