Semiautomatic photometric screening of urine samples for significant bacteriuria with high predictive values

A simple method for screening urine specimens for significant gramnegative bacteriuria is presented, in which microtitration plates, a vertical-beam photometer used for reading ELISA and an inexpensive microcomputer are employed. The wells of the plate containing brain-heart infusion broth are inoculated with urine. Every hour turbidity is measured and the values are compared with the original ones. The whole examination is terminated in five hours. At the actual prevalence of 0.27, specificity is 0.97, the predictive value of a negative result is 0.97 and false positives 0.03. The method is used for rapid reporting to the ward, and for subsequent differentiated standard cultivation.