Different counts in MacConkey Agar

Lynn kees.lyn at xtra.co.nz
Mon May 29 07:19:18 EST 2000


david.lawton1 wrote:
> 
> "Lynn" <kees.lyn at xtra.co.nz> wrote in message
> news:3930ECAC.728D at xtra.co.nz...
> > david.lawton1 wrote:
> > >
> > > "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
> >
> >
> > Why is it not recommended for water counts, what would be more suitable?
> > Lynn
> 
> Membrane lauryl sulphate broth, presuming your looking for E. coli or
> coliforms
> Dave


Thanks Dave, our lab may be doing water testing soon and Im just
starting to sort out what tests to use.
Lynn






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