Evaluation of the MS-2 Urine Screening System

A total of 1,736 urine specimens were evaluated in a two-phase study, and the results were compared with those obtained by the standard semiquantitative culture plate method. In phase 1, 1,083 urine specimens were examined by utilizing modified broth containing 0.03% agar, whereas 653 specimens in phase 2 were examined after preincubation of the same broth overnight at 35 degrees C. In both phases of the study, more than one-half of the total urine samples (54%) were negative (less than or equal to 10(3) CFU/ml), and approximately 16% had colony counts of less than or equal to 10(5) per ml. The sensitivity and specificity in phase 1 were 99.5 and 70.5%, respectively, compared with 92.6 and 83.8% in phase 2. Preincubating the urine ampvettes at 35 degrees C reduced the false-positive rate from 21.9 to 10.5%. The performance requisites of acceptable sensitivity and specificity appeared to be met by the MS-2 (Abbott Laboratories, Diagnostics Div., Dallas, Tex.) screening method.