A urine culture is a test to detect and identify organisms (usually bacteria) that may be causing a urinary tract infection (UTI). Urine in the bladder normally is sterile�it does not contain any bacteria or other organisms (such as fungi)�but a urine sample can pick up bacteria in the urethra during urination.

A urine sample is kept under conditions that allow bacteria and other organisms to grow. If few organisms grow, the test is negative. If organisms grow in numbers large enough to indicate an infection, the culture is positive. The type of organisms causing the infection are identified with a microscope or by chemical tests.