The efficacy of the nitrite test and microscopic urinalysis in predicting urine culture results

The efficacy of the nitrite dipstick and microscopic urinalysis in predicting culture results were evaluated for 146 urine cultures from 56 women at risk for recurrent pyelonephritis. There were 111 negative cultures, 18 positive cultures, and 17 contaminated cultures. Nitrites were not detectable in either negative or contaminated cultures. Bacilluria was present in 10% of negative cultures and in 18% of contaminated cultures. Pyuria was present in 14% of negative and in 24% of contaminated cultures. Among the 18 positive cultures, nitrite was present in only 22%, bacilluria in only 61%, and pyuria in only 67%. These results suggest that positive cultures cannot be accurately predicted by either microscopic urinalysis or the nitrite dipstick, and that routine culturing should be performed as part of the outpatient management of women at risk for recurrent pyelonephritis.