Urinary Tract Infection - Introduction

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• Uncomplicated infections are only associated with bacterial infection, most often Escherichia coli (E. coli). They affect women much more often than men.
• Complicated infections, which occur nearly as often in men as women, are also caused by bacteria but they occur as a result of some anatomical or structural abnormality. Often they are associated with catheter use in the hospital setting, bladder and kidney dysfunction, or kidney transplant (especially in the first three months after transplant). Recurrences occur in up to 50 - 60% of patients with complicated UTI if the underlying structural or anatomical abnormalities are not corrected.

Classifications Based on Symptoms and Levels of Infection. UTIs can also occur without symptoms and with symptoms but very low bacterial levels.

• When bacteria are present and there are no symptoms it is called asymptomatic UTI or also bacteriuria.
• Some patients can also have symptoms of infection with very low bacterial counts. In such cases, the condition is called acute urethral syndrome.

Uncomplicated Urinary Tract Infections (UTIs)

Cystitis. Cystitis is the most common urinary tract infection and is sometimes referred to as acute uncomplicated UTI. It occurs in the lower urinary tract (the bladder and urethra) and nearly always in women. In most cases, the infection is brief and acute and only the surface of the bladder is infected. Deeper layers of the bladder may be harmed if the infection becomes persistent, or chronic, or if the urinary tract is structurally abnormal.

Pyelonephritis (Kidney Infection). When infection spreads to the upper tract (the ureters and kidneys) it is called pyelonephritis, or more commonly, kidney infection. As many as half of all women with cystitis may have infections of the upper urinary tract at the same time as cystitis.

Click the icon to see an image of the kidney.

Urethritis. When infection is limited only to the urethra, the infection is known as urethritis. This is a common sexually transmitted disease in men.