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Methanol Fixation

Dilworth bactitech at hortonsbay.com
Fri Jul 20 10:12:47 EST 2001

We just drop a couple of drops on the smear, let it dry, then perform a
gram stain. At my previous employer, we just used the 50-50
acetone/alcohol decolorizer for fixing as the first step.  We squirted
some of the decolorizer on the slide, let it set for a minute, then
started the gram stain after tipping off the decolorizer.  My current
Ph.D. says that methanol is better than using the decolorizer, though. I
personally can't tell.

We keep the methanol in a dropper bottle by the sink.  I've performed
hundreds of gram smears using the different alcohol fixations described
above in my work as a medical microbiologist in a clinical laboratory. 
It is particularly good for preserving things like trichomonads on
genital smears.  Depending upon the smear, you can sometimes see the
flagella on the gram stains.  The safranin step of the gram smear should
be increased to two minutes (per my previous lab) to ensure that you can
see the trich.

Judy Dilworth, M.T. (ASCP)
Microbiology 27 years

Joyce & Tim wrote:
> Does anyone have any information or a procedure for methanol fixation in
> bacterial smear preparation. I understand this technique produces less
> damage during prep since heating with a burner or incinerator is not
> required.
> T. Burger
> Dept. of Biological Sciences
> Scott Community College
> 500 Belmont Road
> Bettendorf, IA 52722
> tburger at eiccd.cc.ia.us

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