Detection of asymptomatic bacteriuria in obstetric patients with a semiautomated urine screen

Urine specimens (1215) from obstetric patients were evaluated for the presence of significant bacteriuria by the Bac-T-Screen (Marion Scientific Division, Marion Laboratories, Inc., Kansas City, Missouri) and a conventional semiquantitative culture method. Seventy (5.8%) specimens were not processed successfully by the Bac-T-Screen because pigments interfered with interpretation or the test filters clogged. The remaining 1145 specimens screened by the Bac-T-Screen were compared with a conventional culture method. The sensitivity, specificity, positive predictive value, and negative predictive value for specimens containing ≥ 10⁵ colony-forming units per milliliter were 97.4%, 70.4%, 19.0%, and 99.7%, respectively. These values for specimens containing ≥10⁴ colony-forming units per milliliter were 92.2%, 71.6%, 24.1%, and 98.9%, respectively.