Use of nitroblue tetrazolium (NBT) test in the differentiation between pyelonephritis and cystitis.

NBT tests were performed on blood from 37 patients with urinary tract infections caused by coliform bacteria. The level of infections was evaluated by the clinical signs, ESR, renal concentrating capacity and titre of antibodies against the strains of E. coli isolated in their urine. Elevated proportions of NBT-positive neutrophils were found in 11 of 14 patients with pyelonephritis and in 3 of 23 patients with cystitis or asymptomatic bacteriuria (ABU). The total number of NBT-positive neutrophils was 1000 or more per mm3 blood in 11 of 13 patients considered to have pyelonephritis, while it was 800 or less in all the patients investigated, evaluated as having cystitis or asymptomatic bacteriuria. The NBT test is recommended as an adjunct in the level diagnosis or urinary tract infections in children. The utility of the test in smouldering pyelonephritis is presently being investigated.