Nitrite

However, not every type of bacteria is able to form nitrite. Those bacteria that can do it are also called nitrite-forming bacteria. A urinary tract infection can be triggered by both nitrite-forming and non-nitrite-forming bacteria. Thus, a negative nitrite detection is not an exclusion criterion for a urinary tract infection. Even if nitrite-forming bacteria are present in the urine and are the cause of a urinary tract infection, it can happen that the nitrite detection is negative. The reasons for this are manifold.

For one thing, the urine may not have been in the urinary system long enough before it was excreted and examined. The bakeries did not have enough time to form nitrite at all. For a reliable test result, the urine should have been in the urinary system for more than four hours before it is delivered and tested. Therefore, for urine tests, the morning urine is usually used. Even if the urine is heavily diluted due to large amounts of drinking, the nitrite test may be negative even though there is a urinary tract infection.

In addition, it may be that the urine contains little nitrate, so that the bacteria lack the starting material for nitrite synthesis. Causes of low nitrate content in the urine can be a one-sided diet, malnutrition, artificial nutrition or breast milk nutrition in infants.

Furthermore, taking antibiotics can kill existing bacteria and disrupt nitrite formation.