About Nitrite (Urine)
Nitrite in the urine is produced when bacteria convert urinary nitrates using an enzyme called nitrate reductase — making a positive nitrite dipstick highly specific for bacterial infection of the urinary tract. Combined with a positive leukocyte esterase, a positive nitrite result has very high specificity for UTI and is often used to guide empirical antibiotic treatment while culture results are pending. A negative nitrite does not rule out UTI, as some bacteria (including Enterococcus) lack nitrate reductase.