[Histonet] Making gram controls

Katrina Reek k_reek <@t> yahoo.com
Wed Mar 16 14:25:31 CDT 2011

I don't have a written procedure to forward to you, but this is what we do when we make our gram controls. We use fresh tissue from an autopsy before it goes in formalin (such as lung, we've used placenta before as well). Then put a couple pieces of the fresh lung into containers labeled gram +, and gram - (if you want two pieces of tissue on your control; if you're Pathologists prefer a single tissue on the control with both bugs in them, the you'd only need one container).We get the next steps done with assistance from our Microbiology department. Pour broth (not sure what they use, can get that for you as well if you need) into each of the two containers and then inoculate the gram + container with the appropriate bacteria. Do the same with the gram -'s. Incubate the containers at 37degree's for 24-48hrs. We then pour formalin into the containers and let them fix. Dump the formalin and then put the tissue in labeled cassette's, process them,
 embed, and cut them to make sure they stain properly and both sets of bacteria are present. We then seal the blocks back up with more paraffin. They seem to last longer that way for us. 
I googled the topic, and these were steps I found online - although they were for micro, I altered some steps to fit into working for Histo.
Katrina Newell, HT(ASCP)
Crittenton Hospital Medical Center
Rochester, MI 48307


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