<prompt> Eiken test is which type of reaction used for E. coli?PrecipitationAgglutinationToxin antitoxin assayCFT  <response>: Eiken test is a precipitation reaction. Option 1 Eiken Precipitation test Precipitation in Gel Immunodiffusion. Detect heat labile LT enterotoxin. ve for heat labile LT enterotoxin of E.coli. -ve for heat stable ST enterotoxin of E.coli. Types of immunodiffusion reactions: 1. Single diffusion in one dimension Oudin procedure 2. Double diffusions in one dimension Oakley-Fulthorpe procedure 3. Single diffusion in two dimensions Radial immunodiffusion 4. Double diffusion in two dimensions Ouchterlony procedure Eleks test diphtheria toxin Eiken test E.coli toxin Option 2 Agglutination is more sensitive than precipitation test and the clumps are better visualized and interpreted. Option 3 Examples of Neutralization Test: Viral neutralization test: Detects viral neutralizing antibodies. Plaque inhibition test: Done for bacteriophages. Toxin-antitoxin neutralization test. Option 4 CFT complement fixation test detects complement fixing antibodies in the patients serum. 