ABSTRACT
The diagnostic criterion of a single species at a concentration of≥10colony-forming units/ml in a clean-voided urine sample from an asymptomatic patient continues to be a generally accepted definition of significant bacteriuria. Many methods are available for screening urine specimens for bacteriuria. These include microscopic, chemical, culture, and automated techniques. The automated methods which are available for use in the diagnostic laboratory may be divided into three groups based on the principles of detection and their detection times. The most rapid method is colorimetric filtration since results are available within 2 min. This system is based on the presence of bacteria in urine, rather than growth. The second group of automated bacteriuria screening methods utilizes the principle of bioluminescence for detection. The third group requires growth of the organism prior to detection and, therefore, results are somewhat delayed. The three instruments which detect bacterial growth in urine are the Autobac®system, the Auto-Microbic®system, and the Avantage/MS®-2 system.
