Immunomagnetic separation of Salmonella from foods and their detection using immunomagnetic particle (IMP)-ELISA.
An immunomagnetic particle based ELISA (IMP-ELISA) for the detection of Salmonella from foods has been developed using Dynabeads anti-Salmonella (Dynal, Oslo, Norway). Appropriate sample preparation protocols to allow rapid detection of Salmonella serovariants in processed (powdered egg products) and non-processed (raw chicken) samples have been established. Pre-enriched broths of heat processed samples likely to harbour only low levels of competitive enteric flora, were boiled and used directly for IMP-ELISA. For non-heat processed or raw samples likely to contain higher numbers of such competing organisms, live Salmonella cells were first isolated by immunomagnetic separation (IMS) from standard pre-enrichment broths, and then post-selectively enriched for a short time in M-broth followed by boiling before IMP-ELISA. The total assay time including sample preparation was under 26 h for both types of procedure, with a lower detection limit of 10(5) Salmonella cells/ml of sample. In an evaluation of naturally contaminated poultry samples, all 45 of 48 samples previously shown to contain salmonellae in a comparison of ISO, IMS-Plating, Salmonella-Tek ELISA (Organon Teknika, Inc. Durham, NC) and a modification of the latter based on IMS, were identified as positive. None of the other methods gave positives for all 45.
Dynal Microbiology R and D, Oslo, Norway.
K S
KS
Cudjoe
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T
Hagtvedt
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R
Dainty
D000818:Animals; D000942:Antigens, Bacterial / Q000302:isolation & purification; D002645:Chickens; D004531:Eggs / Q000382:microbiology*; D004797:Enzyme-Linked Immunosorbent Assay; D005240:Feasibility Studies; D005516:Food Microbiology; D018189:Immunomagnetic Separation; D008460:Meat / Q000382:microbiology*; D012475:Salmonella / Q000276:immunology / Q000302:isolation & purification*; D012680:Sensitivity and Specificity
D000942:Antigens, Bacterial