title: Detection of Escherichia coli using immunomagnetic separation and bacteriophage amplification coupled with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.
abstract: The application of whole cell analysis by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) has emerged as a valuable tool for rapidly identifying/detecting bacteria. This technique requires minimal sample preparation and is simple to perform, but is generally limited to purified samples of bacteria at concentrations greater than 1.0 x 10(6) cells/mL. In this paper, we describe a bacterial detection method that integrates immunomagnetic separation with bacteriophage amplification prior to MALDI-MS analysis. The developed method consists of three main stages: (1) isolation of a target bacterium by immunomagnetic separation; (2) infection of the immuno-captured bacterium with a lytic bacteriophage; and (3) assay of infected medium for bacteriophage progeny using MALDI-MS to produce a molecular weight signal for the virus capsid protein. With this technique, the presence of Escherichia coli in broth was determined in less then 2 h total analysis time at a concentration of approximately 5.0 x 10(4) cells/mL.
authors.affiliation: Department of Chemistry, Colorado School of Mines, Golden, CO 80401, USA.
authors.forename: Angelo J
authors.initials: AJ
authors.lastname: Madonna
authors.forename: Sheila
authors.initials: S
authors.lastname: Van Cuyk
authors.forename: Kent J
authors.initials: KJ
authors.lastname: Voorhees
mesh_terms: D001435:Bacteriophages / Q000235:genetics / Q000302:isolation & purification*; D004926:Escherichia coli / Q000302:isolation & purification* / Q000821:virology*; D018189:Immunomagnetic Separation / Q000379:methods*; D008828:Microbiological Techniques; D012680:Sensitivity and Specificity; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*