Recovery of Escherichia coli 0157:H7 from mixed suspensions: evaluation and comparison of pre-coated immunomagnetic beads and direct plating.
Escherichia coli O157:H7 has become an important enteropathogen, causing sporadic outbreaks of haemorrhagic colitis. However, it has not so far been isolated from suspect foods, which may be due to low numbers, sub-lethal injury, or overgrowth by other organisms. Immunomagnetic separation could provide an answer to these problems. The technique utilises antibody-coated magnetic polymer beads and is considered fast, safe, sensitive and reproducible. Commercially produced polymer beads coated with a polyclonal antibody were standardised and compared with direct plating to maximise recovery of Esch. coli O157:H7 from mixed suspensions. An increase in sensitivity was found, but this was offset by a loss of specificity.
Mortlock
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Guildford Public Health Laboratory, St Luke's Hospital, Surrey, England, UK.
D001431:Bacteriological Techniques; D004926:Escherichia coli / Q000302:isolation & purification*; D005516:Food Microbiology; D018189:Immunomagnetic Separation / Q000379:methods*; D012680:Sensitivity and Specificity