Evaluation of a new sensitive nitrite test as a reliable screening tool for bacteriuria.

A new sensitive nitrite test, the SRN test, was evaluated for its suitability as a reliable screening technique for the detection of bacteriuria. The SRN test was compared to a currently available nitrite test, the Microstix nitrite test, and the results obtained with both nitrite tests were assessed in comparison with the results of the quantitative culture method. Of 158 cases of significant bacteriuria found among 1060 randomly collected specimens, the SRN test detected 90% and the Microstix nitrite test, 30%. The higher reliability of the SRN test reflects its high capability of nitrite detection (greater than or equal to 0.1 ppm), and its ability to overcome interference by various factors, such as dark colour of the urine, presence of phenazopyridine, urobilinogen, blood, high concentration of ascorbate, and high urinary pH, all of which do interfere with the Microstix nitrite test. The high sensitivity of the SRN test allows detection of bacteriuria in urine specimens collected at random throughout the day; the test is therefore not restricted to the use of first-morning samples as are other nitrite tests. Since the SRN test was found to give a quantitative indication of the size of the bacterial population, the possibility of its use as an exact quantitative test under controlled conditions its discussed.