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Different counts in MacConkey Agar

david.lawton1 david.lawton1 at ntlworld.com
Fri May 26 20:55:56 EST 2000


"Yjgent" <yjgent at aol.com> wrote in message
news:20000526213618.02915.00000277 at ng-fz1.aol.com...
> >In this lab we're working with E.Coli (ATCC 25922 and wild type) and we
> >routinely use MacConkey Agar inclusion plating as a counting method for
> >these microorganisms.
>
> I was taught a long time ago NOT to measure a colony count from a Mac
plate.
> Only a non selective agar like TSA or a Blood Agar plate can be used to
count
> colonies.
> John Gentile M(ASCP)                   President - Rhode Island Apple
Group
> yjgent at aol.com
> Microbiologists do it with culture.
Depends on the formulation and what you are trying to count.
For years we used a MacConkey that surpressed gram - positives combined with
a blood agar for urine.
You can use Mac for water counts, though not recommended

Dave







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