Urinary Tract Infection - Introduction

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• Reinfection. About 80% of recurring UTIs are reinfections. A reinfection occurs several weeks after antibiotic treatment has cleared up the initial episode and can be caused by the same bacterial strain that caused the original episode or a different one. The infecting organism is usually introduced through fecal bacteria and moves up through the urinary tract.
• Relapse. Relapse is the less common form of recurrent urinary tract infection. It is diagnosed when a UTI recurs within 2 weeks of treatment of the first episode and is due to treatment failure. Relapse usually occurs in kidney infection (pyelonephritis) or is associated with obstructions such as kidney stones, structural abnormalities or, in men, chronic prostatitis.

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Asymptomatic Urinary Tract Infection (Asymptomatic Bacteriuria)

When a person has no symptoms of infection but significant numbers of bacteria have colonized the urinary tract, the condition is called asymptomatic UTI (also called asymptomatic bacteriuria). The condition is harmless in most people and rarely persists, although it does increase the risk for developing symptomatic UTIs.

Screening for asymptomatic bacteriuria is not necessary during most routine medical examinations, with the following exceptions:

• Pregnant women. Pregnant women with asymptomatic bacteriuria have an increased risk of acute pyelonephritis in their second or third trimester. Therefore, they need screening and treatment for this condition. Guidelines recommend that pregnant women be screened for asymptomatic bacteriuria at 12 - 16 weeks gestation or at the first pre-natal visit, if later.
• People undergoing urologic surgery (such as prostate surgery in men). The presence of an infection during surgery can lead to serious consequences.

Review Date: 06/17/2010
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org).