Screening urine samples for significant bacteriuria in the clinical microbiology laboratory

Abstract

Urine specimens for quantitative bacteriologic culture represent one of the most common samples submitted to the clinical microbiology laboratory for testing. Although quantitative urine culture represents the established “gold standard” for the laboratory diagnosis of a urinary tract infection, it represents a labor-intensive, time-consuming, and expensive activity in which over 60% of all samples processed show no evidence of significant bacterial growth. Several semi-automated and automated systems have been developed for the initial screening of urine samples for detecting the presence of significant bacteriuria. The availability of such a reliable urine screening device would eliminate the need to perform quantitative culture on urine samples that contained insignificant numbers (i.e., less than 10,000 CFU/ml) and the generation of a final “negative” culture report within several hours of specimen receipt. This report reviews the reliability of various urine-screening methods and instruments in identifying urine samples that contain significant bacteriuria.