A negative urine test for nitrite is normal; when the result is positive, it is abnormal and indicates the presence of an infection of the genus Enterobacter, especially Escherichia coli. Escherichia coli infection can reduce nitrate to nitrite in the urine, resulting in a positive result, and may be accompanied by an increased number of white blood cells in the urine or symptoms of an associated urinary tract infection. Positive nitrite results can also occur in patients with long-term indwelling urinary catheters, cystostomy tubes, and nephrostomy tubes, which are associated with the long-term presence of the tube in the urinary tract and the development of colonizing bacterial infections. If no infection of Enterobacter spp. has occurred, a positive nitrite result will not occur, and a negative nitrite result is indicated, which is a normal result. Routine urine tests for leukocyte esterase, bacterial count and white blood cells are also indicators of infection and need to be combined to make a determination if an infection has occurred.