[Evaluation of a new method for urine screening based on the study of catalase]

A new method of urine screening based on the enzymatic study of catalase (Uriscreen) was evaluated. Catalase is produced by the majority of microorganisms that cause urinary infections as well as by red cells, uroepithelial cells and PMN. In 553 consecutive urine samples we studied the sediment, the conventional culture, and the Uriscreen test. Comparative study between culture and Uriscreen revealed a sensitivity of 92.3%, specificity of 83.3%, negative predictive value of 96.2%, and positive predictive value of 69.9%. In 86% of the samples the results obtained with both techniques were similar, whereas in 14% of the cases they failed to coincide. Among the 74 cases of disagreement, 12 were false negative (culture positive, Uriscreen negative) and 62 were false positive (culture negative, Uriscreen positive). The high sensitivity and negative predictive values obtained with the screening method indicate that this is an useful procedure for the study of negative urines since it allows to rapidly classify 60.2% of the samples.