We used to incubate newly poured plates uninoculated overnight to check
for any quickly growing contaminants before bagging the plates up. You
can also try that.
We used to pour our plates out on a counter top, i.e. NOT in a sterile
hood, and never had any trouble with contaminants. You must work quickly
and put the lids on. We even put the lids on a little off-center to
allow condensation to escape for a half hour or so before totally
lidding them and never had problems. We used to hand make all of our
MacConkey, Sabourauds (fungal media), Mycosel (fungal media), XLD (stool
media), and lots of specialty agars for certain organisms. It isn't as
touchy as one might think. The touchiest part is making sure the agar is
dissolved totally but not burnt and that it doesn't boil over once it
starts boiling. You should only boil for a minute, tops, or the media
will burn. We used to make 2 lites of media at a time, boil it up, put
it in the autoclave to sterilize, then put in a hot water bath until it
cooled down to just above the setting temperature to pour the plates. It
takes awhile to get the hang of it. We also made lots of different kinds
of slants.
We make virtually no media nowadays, as there just isn't time. In the
olden days we had ladies in our "kitchen" who would wash out all the
tubes after autoclaving and then we would recycle everything. Sadly that
is not done any more. It seems like a waste, but hospitals would rather
buy everything than pay benefits to anyone to make the stuff. It seems
pretty dumb to me.
Judy Dilworth, M.T. (ASCP)
Microbiology
EK wrote:
I am more concerned about contamination that might eventually take over
unless you poured and wrapped your plates in the strictly aseptical
environment such as sterile hood, which you probably did not.
