AW: [Histonet] Stain vs dye and control

[Gudrun Lang]

Hi Jorge,
Not all histolabs have access to fresh cultures. So they search an easy way to get bacterial controls. And things like sausage are more like the usual specimens than liquid samples.

The best staining control is an inhouse-specimen, that is processed in the same way as any other specimen (preanalytic, fixation, processing, cutting, staining). But sometimes this is not possible, so one uses the "next-best".
A control with known ingredients (like bacteria) can be used to check the whole process and must be positive for the tested parameter. A patient-sample can only be considered positive or negative, if the positive-control proves the functionality of the process (staining-protocol).

Dye and stain. You can touch the dye, but not the stain.  And then you have got stained fingers. ;-)

Gudrun



-----Ursprüngliche Nachricht-----
Von: histonet-bounces <@t> lists.utsouthwestern.edu [mailto:histonet-bounces <@t> lists.utsouthwestern.edu] Im Auftrag von Jorge A. Santiago-Blay
Gesendet: Freitag, 06. März 2015 21:49
An: Histonet <@t> lists.utsouthwestern.edu
Betreff: [Histonet] Stain vs dye and control

Dear Histonetters:

Last semester I taught a microbiology lab and, as I was reviewing for class, noticed some lack of precision in the use of the terms "dye" vs.
"stain" in biology. Could someone help?

While I am on "stains", I have been following the emails on controls and wonder a couple of things.

1. What would testing for bacteria on beef jerky, hot dogs or burgers accomplish that is different (ideally better) that what one accomplishes by pulling out from fresh cultures out of a medium (e.g. liquid, such as broth, solid, such as slabs, agar)?  Is it the idea to test for bacteria in an animal tissue? If so, would a solid medium (like someone mentioned recently, such as agar) do?

2. An advantage of using fresh bacterial cultures of known Gram is that it could be used to test whether the reagents are good enough. Last semester I had the suspicion that one (or more) of our Gram reagents where not up to par.

If you have any feedback, please feel free to email me directly at blayjorge <@t> gmail.com . Thank you.

Sincerely,

Jorge

Jorge A. Santiago-Blay, PhD
blaypublishers.com
http://blayjorge.wordpress.com/
http://paleobiology.si.edu/staff/individuals/santiagoblay.cfm
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