Antibiotic shelf life?

Emmanuel Skoufos, Ph.D. skoufos at
Sat Mar 11 17:17:39 EST 1995

"William C. (Bill) Johnson" <ez003195 at> writes:
>General question - how long do most antibiotics retain their effectiveness?
>Specifically - how useful is, say, the four year old tube of ampicillin I 
>found in the -20 freezer?  I've been told that most antibiotics in an 
>agar plate are only good for a few weeks, and now I wonder about our stocks.

Freezer stocks are usually good for up to six months at -20, one year at -80.
At least this is the guidelines we've been using.  You may want to try pouring
a couple of plates with your old amp and see whether amp sensitive bacteria
will grow.



Emmanuel Skoufos, Ph.D.
Insect Molecular Biology Group
Institute of Molecular Biology and Biotechnology
Box 1527 
Heraklion, Crete 71110

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