The basic agar for blood agar media can vary. Listeria doesn't need anything
extra special.
In operating rooms etc. blood agar plates can be placed to determine if Staph.
aureus is present in the air. Most labs would use MSA (selective), but many labs
prefer blood agar.
If our hospital pharmacy wants to check their "sterile" room, we give them blood
agar, to catch as much as possible. They do not look specifically for certain
kinds of bacteria or moulds.
Loes
Austin Reade wrote:
> Not being a clinical microbiologist I have not used blood agar for anything
> other than foodborne Listeria id work so I just looked up its composition.
> According to an American Society of Microbiology general micro text, it is
> essentially tryptic soy agar (also known as trypticase soy agar and
> soybean-casein digest agar) with the blood added to this base.
>> This isn't the sort of medium one would "normally" (there are always
> exceptions I'm sure) use for environmental air surveys. TSA without the
> blood works well as someone noted already. However, if you are looking
> particularly for molds it would be better to use one of the numerous malt
> extract agar formulations supplemented with antibiotics to suppress
> bacteria, and rose bengal to prevent excessive spread of mold colonies. We
> also use a medium called DG18 which is a low water activity formulation
> designed to select for xerophilic/xerotolerant molds which can often be
> found in air samples and which don't compete well on high water activity
> media.
>> Of course if you are looking for airborne bacteria which can hydrolyse blood
> cells then I guess blood agar makes a lot of sense.
>> I receive isolates of fungi from a pharmaceutical company for ID and these
> are always on blood agar plates. In order to identify to species the
> isolates are always transferred to different media (MEA, CYA, etc) as their
> morphology on blood is unusual (to me at least).
>> --
> Austin Reade, PhD, RSM(CCM)
> Reade BioSciences Inc phone (902)423-8369
> 1136 Cartaret Street fax (902)423-8313
> Halifax, NS, B3H 3P3 Canada email rbs at hfx.andara.com>> David Lawton <dhlawton at clara.co.uk> wrote in message
> news:0rSC4.3987$pQ5.90150 at nnrp3.clara.net...> > The brain's not working this evening - I do know what oligotrophic
> bacteria
> > are, just not used to using the posh name.
> > Yeast extract agar is recommended for water samples in the UK.
> > For general air samples tryptone soya agar is often recommended, however
> for
> > our routine use we find no trouble using blood agar. Depends of cause why
> > you're taking the air samples
> >
> > I still wouldn't call blood agar isn't a selective medium though.
> >
> > A medium that doesn't grow an organism as well as another one doesn't mean
> > it's selective.
> >
> > To my mind a selective media is something where an ingredient is added to
> > make it selective for a specific organism or group of organisms.
> > If you added, for example, nalidixic acid and colistin then you have a
> > selective medium.
> >
> > --
> > David Lawton
> >
> > "lamb" <L.A.M.Buisman at cable.A2000.nl> wrote in message
> > news:38DBC8FB.8DCCDF6A at cable.A2000.nl...> > > David Lawton wrote:
> > >
> > > > As I know nothing about oligtrophic bugs I can't comment,
> > > > but being highly pedantic, for air samples wouldn't blood agar be
> > considered
> > > > a non - selective medium
> > > > especially when compared with nutrient agar.
> > >
> > > For culturing watersamples nutrient agar or R2A is recommended. We find
> a
> > > 100-1000 fold increase in colony count compared to blood agar.
> > > Air samples can show fantastic amounts of growth on bloodagar. Usually
> the
> > whole
> > > lot gets overgrown with molds.
> > >
> > > Loes
> > >
> > >
> >
> >
