Submitted to: Journal of Rapid Methods and Automation in Microbiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/14/2006
Publication Date: 12/14/2006
Citation: Gehring, A.G., Irwin, P.L., Reed, S.A., Tu, S. 2006. Enzyme-linked immunomagnetic chemiluminescence incorporating anti-h7 and anti-0157 antibodies for the detection of escherichia coli 0157:h7. Journal of Rapid Methods and Automation in Microbiology. 14:349-361. Interpretive Summary: Escherichia coli (E. coli) O157:H7 is a harmful bacterium that has been implicated in numerous cases of foodborne poisonings. A variety of rapid tests, that often require only a few hours for completion, have been created to detect the presence of this bacterium in foods. These screening tests are often used as alternatives to more conventional microbiological methods that take days for an answer. However, most rapid tests are presumptive and therefore do not claim to confirm the presence of E. coli O157:H7 in foods. In an attempt to create better tests, we have shortened the testing time for a rapid test, termed enzyme-linked immunomagnetic chemiluminescence (ELIMCL) that we had recently developed. Furthermore, in order to significantly improve accuracy (selectivity or specificity) we have enhanced ELIMCL to now incorporate two different antibodies instead of one antibody into the ELIMCL technique. This work presents the application of ELIMCL to the detection of E. coli O157:H7 with a detection limit of approx. 100,000 to 1,000,000 live cells per milliliter of a buffered liquid. The testing time requires about 1 hour, total. ELIMCL may be used by food producers to test for the presence of harmful bacteria in their products.
Technical Abstract: The pathogenic bacteria Escherichia coli O157:H7 has been associated with numerous cases of food borne illnesses. Many rapid methods have been developed for the screening of this pathogen in foods in order to circumvent timely plate culture techniques. However, many of these methods are presumptive and do not claim to confirm the presence of E. coli O157:H7. Using a relatively affordable and portable chemiluminescent detection method coupled with an enzyme-linked sandwich immunoassay and paramagnetic microparticles (enzyme-linked immunomagnetic chemiluminescence; ELIMCL), we have developed a rapid method that shows promise for confirming the presence of E. coli O157:H7. The key feature of this assay is that it combines the highly selective synergism of both anti-O157 and anti-H7 antibodies in the sandwich immunoassay format. This work presents the application of a one-step ELIMCL to the detection of E. coli O157:H7 in pristine buffered saline with apparent detection limits of approx. 100,000 to 1,000,000 of live cells per milliliter. In addition, the immunoassay portion of this method is performed in a one-step format that accommodates a total assay time of approx. 1 hr.