As you can see this part of the forum is focused on food safety and water quality. We have it broken down into pathogen types but if you think there is a better way to organize it please add you suggestions to this thread. Thanks.

Has anyone seen anything on the use of a 2x media for the enrichment of E. coli O157:H7? I work for a small meat plant and we conduct our own E. coli sampling, but the amount of liquid sample is cumbersome. Any information would be a big help.

Our research lab often uses a 2x concentrate of enrichment broth when culturing liquid samples (water) for E. coli O157. This seems to work well and is accepted in research circles, however, for regulatory purposes this may not be approved. Feel free to provide more details or contact me directly if you wish to discuss in more depth.

Thank you for the info. We are currently using mEC with Novobiocin enriching at a 1:10 dilution of the meat sample. We are under FSIS inspection. I have a very small lab and anything that would decrease the amount of waste to destroy in my autoclave would be helpful.

For the 2x concentrate, are you then using smaller volumes of the media? There is some discussion among FSIS allowing plants to use a 1:5 dilution, but I am unsure if that will provide enough nutrients.

Hrolla - To make it easier for people to follow the conversations, it helps to start a "New Topic" when you have a question. If a thread already exists and you want to answer a question or make a comment, use the "Post Reply" button. Thanks.

I am not sure of the FSIS requirements or changes. I do know that the volume of broth in relation to the the weight of sample is fairly critical- bacteria may tend to grow to saturation, usally no more than 10^8 or 10^9 per ml. For you, I believe that the size of the sample is dictacted by FSIS, (375g?). Therefore, I don't see a way of reducing the volume- sorry.

If the total number of bacteria reach this level before E. coli O157 achieves detection level, then they will cease to multiply (exahustion of nutrients, productions of by-products) and the E. coli O157 may never reach the level you need.