Fountain Flow™ cytometry, a new technique for the rapid detection and enumeration of microorganisms in aqueous samples

Abstract

Background: Pathogenic microorganisms are known to cause widespread waterborne disease worldwide. There is an urgent need to develop a technique for the real-time detection of pathogens in environmental samples at low concentrations, <10 microorganisms/ml, in large sample volumes, ≥100 ml. Methods: A novel method, Fountain Flow™ cytometry, for the rapid and sensitive detection of individual microorganisms in aqueous samples is presented. Each sample is first incubated with a fluorescent label and then passed as a stream in front of a laser, which excites the label. The fluorescence is detected with a CCD imager as the sample flows toward the imager along its optical axis. The feasibility of Fountain Flow cytometry (TFC) is demonstrated by the detection of Escherichia coli labeled with ChemChrome CV6 and SYBR Gold in buffer and natural river water. Results: Detections of labeled E. coli were made in aqueous suspensions with an efficiency of 96% ± 14% down to a concentration ∼200 bacteria/ml. Conclusions: The feasibility of FFC is demonstrated by the detection of E. coli in buffer and natural river water. FFC should apply to the detection of a wide range of pathogenic microorganisms including amoebae. © 2006 International Society for Analytical Cytology.