A positive nitrite test suggests the presence of a minimum of 105 microorganisms / mL in your urine. The nitrite test in urine is a method used to detect the presence of microorganisms in the urine. This is a diagnostic test for urinary tract infections. Microorganisms that are the cause of UTI or urinary tract infection produce an enzyme that would change nitrates in urine into nitrite. This nitrite that is formed is the ion that is monitored and measure in a nitrite test. If nitrites are present in the urine, then most probably UTI is present. A positive in this test is called nitrituria.