Sounds like contamination to me.
I've not seen gram positves growing in VRGBA, not with the samples we test
anyway
and if they are creamy white colonies then they aren't glucose positive,
might be an Acinetobacter or an odd Pseudomonas.
--
Dave
"lamb" <L.A.M.Buisman at cable.A2000.nl> wrote in message
news:38EF8BD3.4390F5D6 at cable.A2000.nl...
> Tim Marsh wrote:
>> Were the control plates overlayed with agar at the same time as the plates
in
> the test? If not, maybe contamination took place while pouring the second
> layer.
> It could be that what grew is a strictly aerobic bacterium. Bacillus sp.?
What
> kind of sample was cultured?
> Is it grampositive? Spores?
> The next step depends on the kind of lab you're in, what tests are
available.
>> Loes
>> > Dear All,
> >
> > A colleague has been carrying out tests for Enterobacteriaceae using
VRB-G
> > (Violet Red Bile agar with Glucose, produced by Oxoid) agar. The test
is
> > carried out as a pour plate using VRB-G, which is also overlaid with
VRB-G.
> >
> > Approx. 60 of the plates have grown creamy white colonies on the surface
of
> > the overlay (not in the original test sample layer). I thought this
might
> > have been environmental contamination, but all control plates used show
no
> > growth.
> >
> > The limited microscopy so far performed indicates that they are
bacterial:
> > small rods (slightly longer than Listeria sp.) and are also motile.
> >
> > Can anyone enlighten me? Can you suggest what they might be or what the
> > next stage of diagnosis might be?
> >
> > Thank you for any help!
> >
> > Tim
> >
> > ( Please reply to tmarsh at wrl.co.uk )
>
