Do you have pain or burning when you urinate? The infections can affect several parts of the urinary tract, but the most common type is a bladder infection (cystitis). A urinary tract infection (UTI) is an infection in any part of your urinary system your kidneys, ureters, bladder and urethra. A urinary tract infection, or UTI, is an infection in any part of your urinary system, which includes your kidneys, bladder, ureters, and urethra.
These include infections with no symptoms (asymptomatic bacteriuria), cystitis (bladder infection) and pyelonephritis (kidney infection). Most UTIs are caused by bacteria, such as Escherichia coli, Klebsiella pneumoniae, or Staphylococcus saprophyticus. When it affects the lower urinary tract it is known as a bladder infection (cystitis) and when it affects the upper urinary tract it is known as a kidney infection (pyelonephritis). Find out about urinary tract infections (UTIs), including what the symptoms are, when to get medical advice and how they're treated.