title: Time-resolved fluorescence-based assay for rapid detection of Escherichia coli.
abstract: Fast and simple detection of pathogens is of utmost importance in health care and the food industry. In this article, a novel technology for the detection of pathogenic bacteria is presented. The technology uses lytic-specific bacteriophages and a nonspecific interaction of cellular components with a luminescent lanthanide chelate. As a proof of principle, Escherichia coli-specific T4 bacteriophage was used to infect the bacteria, and the cell lysis was detected. In the absence of E. coli, luminescent Eu(3+)-chelate complex cannot be formed and low time-resolved luminescence signal is monitored. In the presence of E. coli, increased luminescence signal is observed as the cellular contents are leached to the surrounding medium. The luminescence signal is observed as a function of the number of bacteria in the sample. The homogeneous assay can detect living E. coli in bacterial cultures and simulated urine samples within 25 min with a detection limit of 1000 or 10,000 bacterial cells/ml in buffer or urine, respectively. The detection limit is at the clinically relevant level, which indicates that the method could also be applicable to clinical settings for fast detection of urine bacteria.
authors.affiliation: Laboratory of Biophysics and Medicity Research Laboratories, University of Turku, 20520 Turku, Finland. Electronic address: janne.kulpakko@utu.fi.
authors.forename: Janne
authors.initials: J
authors.lastname: Kulpakko
authors.affiliation: Laboratory of Biophysics and Medicity Research Laboratories, University of Turku, 20520 Turku, Finland.
authors.forename: Kari
authors.initials: K
authors.lastname: Kopra
authors.affiliation: Laboratory of Biophysics and Medicity Research Laboratories, University of Turku, 20520 Turku, Finland.
authors.forename: Pekka
authors.initials: P
authors.lastname: Hänninen
mesh_terms: D017122:Bacteriophage T4 / Q000502:physiology; D004926:Escherichia coli / Q000166:cytology / Q000302:isolation & purification* / Q000821:virology; D006801:Humans; D028581:Lanthanoid Series Elements / Q000737:chemistry; D057230:Limit of Detection; D008163:Luminescent Measurements; D013997:Time Factors
chemical_list: D028581:Lanthanoid Series Elements
keywords: Bacteriophage; Escherichia coli; Luminescence; Urinary tract infection