Search Thermo Fisher Scientific
Search Thermo Fisher Scientific
Enhanced Automated Immunomagnetic |
Dynabeads anti-E. coli O157 are designed for rapid, selective concentration of E. coli O157 directly from a pre enriched sample aliquot using immunomagnetic separation (IMS). Dynabeads anti-E. coli O157 reacts with all E. coli O157 strains including pathogenic and non-pathogenic, sorbitol fermenting and non-sorbitol fermenting isolates. Dynabeads anti-E. coli O157 are easily incubated with an aliquot of the pre-enriched sample and the antibodies coated onto the beads will specifically bind the target bacteria. The bead-bacteria complexes are subsequently separated by applying a magnetic field. The whole IMS process can be automated using a BeadRetriever™ instrument or performed manually. Automated IMS (AIMS) using the BeadRetriever™ allows the user to selectively concentrate E. coli O157 from 15 samples at once. Utilizing a new custom coated MyOne anti-E. coli Dynabead with a greater surface area than the M280 Dynabead and improvement of the BeadRetriever™ protocol with optimized buffers and a higher starting volume of sample, a 60% higher capture rate has been realized over the standard product & protocol. Detection down to 10 CFU/25g of ground meat beef was detectable after only a 4 hour pre-enrichment Inclusion of ChargeSwitch Technology (CST) for the pre extraction of DNA prior to qPCR increased the detection of E. coli O157 to 1CFU/25g of sample with 100% detection of samples at 10CFU/25g of sample. These advances allow testing of up to 15 separate food samples per instrument, in one work day with the high sensitivity required for today’s food market.
No. | CFU/assay | Detection by new E. coli Dynabead (%) | Detection by EPEC/VTEC (%) |
---|---|---|---|
Set 1 | 10 | 80 | 20 |
Set 2 | 100 | 95 | 55 |
Set 3 | 1000 | 97 | 80 |
Set 4 | 10000 | 100 | 100 |
Table 1. The sensitivity of the VTEC enhanced protocol and the standard AIMS protocol were compared by measuring the efficiency of detection at 10, 100, 1000, and 10,000 CFU, from pure bacterial cultures. The Results (Table 1) indicate a 60% difference in the performance of the two methods when 10 CFU of pure bacterial culture are placed in the system.
Level of contamination | Dynal EPEC/VTEC (%) | Dynal eAIMS (%) | Competitor M (%) |
---|---|---|---|
Low | 40 (10CFU/25mg) | 100 (10CFU/25g) | 65 (~5CFU/25g) |
Table 2. Comparison of the original EPEC/VTEC protocol with the enhanced protocol using qPCR as the final detection method. A 6 hour pre-enrichment was used for these samples. Competitor M results are for culture only with a 3 hour pre-enrichment. Reported values for this competitor state a detection level of between 1-10 CFU/25g sample using culture or PCR (AOAC Validation Report).
Figure 1.
1. Khan, A. (2006) University of Central Lancashire, UK
2. Dynabeads anti-E. coli O157, Rev. No. 007, Dynal Biotech, Oslo, Norway
For Research Use Only. Not for use in diagnostic procedures.