Cause

Bacteria that enter the urethra and travel up the urinary tract are the usual cause of urinary tract infections (UTIs). Bacteria that normally live in the large intestine and are present in feces (stool) are the most common source of infection. Sexual intercourse may move bacteria into the urinary tract, especially in women. Catheters, which are small, flexible tubes inserted into the bladder to allow urine to drain, are a common source of bacterial infection in people who are in hospitals or who live in long-term care facilities.

Sometimes bacteria traveling through the blood or lymph system cause kidney or bladder infections.

Kidney stones, an enlarged prostate in men, and structural problems in the urinary tract can contribute to UTIs by limiting the body's ability to eliminate urine completely.

Symptoms

Symptoms of a urinary tract infection (UTI) may include:

• Pain or burning when you urinate.
• An urge to urinate frequently but usually passing only small amounts of urine.
• Dribbling (inability to control urine release).
• Pain or a feeling of heaviness in your lower abdomen.
• Reddish or pinkish urine.
• Foul-smelling urine.
• Cloudy urine.
• Pain in your back just below the rib cage, on one side of your body (flank pain).
• Fever and chills.
• Nausea and vomiting.

Some people have bacteria in their urinary tract without having any symptoms. This is called asymptomatic bacteriuria. These types of infections often affect pregnant women, older adults, and people who need a catheter to urinate. Pregnant women are screened for asymptomatic bacteriuria and treated with antibiotics, because it can cause preterm labor and other problems if not treated. Asymptomatic bacteriuria may lead to infections that cause symptoms, but in many cases it does not. It usually goes away without treatment.

Several other conditions, such as vaginal infections or irritable bladder, cause symptoms similar to those of a UTI. Your doctor may evaluate your health for one or more of these if you have urinary symptoms, depending on your medical history and how well you respond to treatment for a UTI.