[Microbiology] Re: group A strept beta haemolysis
yjgent at cox.net
Sun Dec 11 22:34:05 EST 2005
On 2005-12-10 22:35:22 -0500, "streptoA" <sindhulina at hotmail.com> said:
> Is there any way to find out if beta strept are b haemolytic other than
> by actually plating on sheep blood agar? We find it a little difficult
> to get sheep blood. So we manage with chocolate agar from other blood.
> Just a thought that it would make diagnosis so much easier if there was
> a easier way - like a biochemical test of some kind, or something.
> Anyone wih any ideas on this, please get back to me.
Without seeing the hemolysis and doing some kind of biochemical or disk
test I doubt if you could accurately identify any kind of beta Strep.
There are rapid Strep kits available that will take a swab of the
throat and after an extraction identify the presence or absence of
Strep antigens. Most of these kits are limited to Group A.
You mentioned other blood - I have used Columbia agar with Horse blood
for many years and can tell you that hemolysis for Group A Strep is
very good. However there are other organisms that can also appear
hemolytic on HB that would be non hemolytic on sheep blood.
Are you also using a "Taxo A" disk? This is a test disk that can be
placed on the culture and a zone of inhibition almost always indicates
the presence of Group A Strep. We also confirm that zone with a latex
John Gentile, MS M(ASCP)
Laboratory Information Manager
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