Development and characterization of a fluorescent-bacteriophage assay for detection of Escherichia coli O157:H7.
In this paper we describe evaluation and characterization of a novel assay that combines immunomagnetic separation and a fluorescently stained bacteriophage for detection of Escherichia coli O157:H7 in broth. When it was combined with flow cytometry, the fluorescent-bacteriophage assay (FBA) was capable of detecting 10(4) cells/ml. A modified direct epifluorescent-filter technique (DEFT) was employed in an attempt to estimate bacterial concentrations. Using regression analysis, we calculated that the lower detection limit was between 10(2) and 10(3) cells/ml; however, the modified DEFT was found to be an unreliable method for determining bacterial concentrations. The results of this study show that the FBA, when combined with flow cytometry, is a sensitive technique for presumptive detection of E. coli O157:H7 in broth cultures.
Goodridge
L
L
Department of Food Science, University of Guelph, Guelph, Ontario, Canada, N1G 2W1. mgriffit@uoguelph.ca
Chen
J
J
Griffiths
M
M
D003090:Coliphages; D015169:Colony Count, Microbial; D003470:Culture Media; D019453:Escherichia coli O157 / Q000254:growth & development / Q000302:isolation & purification* / Q000821:virology; D005434:Flow Cytometry; D018189:Immunomagnetic Separation; D008856:Microscopy, Fluorescence; D012680:Sensitivity and Specificity
D003470:Culture Media