Urinary tract infections in childhood: the place of the nitrite test

The effectiveness of the nitrite test available on the N-Multistix (Ames Co.) was compared with that of the microscopic examination of urine as a screening test for the detection of urinary tract infections in children presenting to a general paediatric clinic. The nitrite test gave a positive result in 59% of children with urinary infections, while microscopic pyuria (more than 50 white blood cells per cubic millimetre of uncentrifuged urine) was found in 72% of the same group. Of children who did not have a urinary tract infection, 2.8% had microscopic pyuria compared with only 0.2% who showed a false-positive nitrite test result. The ease and rapidity of the nitrite test make it a useful screening test for the presumptive diagnosis of urinary tract infections, and in certain circumstances it is preferable to the conventional microscopic examination of urine. However, as in the case of microscopic examination, urine culture must always be performed to avoid missing the urinary infections that are not detected by the screening test.