An immune-capturing and concentrating procedure for Escherichia coli O157 : H7 and its detection by epifluorescence microscopy

Escherichia coli O157:H7 cells were captured on a polyvinyl chloride (PVC) sheet coated with polyclonal anti-E, coli O157:H7 antibody, and stained wit h fluorescein-labelled anti-E. coli O157:H7 antibody. The cells were then s craped off the PVC surface in water, concentrated by filtering through a 3- mm diameter area of polycarbonate membrane filter, and counted by epifluore scence microscopy. This procedure was specific for E. coli O157:H7, highly sensitive, allowing detection of E. coli O157. H7 at 4.7 X 10(1) - 1.3 x 10 (2) cfu ml(-1), and required less than 2 h to execute. The presence of anim al tissue fluids lie., beef liver and chicken exudates) or cow faeces did n ot inhibit the capturing of bacterial cells by the antibody-ceased PVC. Alt hough beef liver exudate interfered with filtration and slightly reduced th e number of cells detected, treatment with trypsin improved the filterabili ty but did nos improve detection sensitivity. (C) 1998 Academic Press.