I never had any contamination when pouring plates on the benchtop either.
The point I was trying to make is that since here the original poster wants
to store the plates much longer than usual, I believe whatever contamination
is present on the *outside* of the plates poured under semi-sterile
conditions of the benchtop will eventually find its way into the plates
during prolonged storage. My concern is that when tightly wrapped, plates
will start "leaking" condensate so that whatever contaminants are sitting
just near the place where the lid touches the plate rim, it will take a
chance to swim inside. I have seen that before even with old antibiotic
plates store long enough to lose the activity of the antibiotic.
"JEDilworth" <bactitech at nospamhortonsbay.com> wrote in message
news:3DF032F9.F5D7E62D at nospamhortonsbay.com...
> 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)
>>> 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.