Group A Beta Strep Incubation Time

CAROLYN J. LOCY carolynj at
Thu Sep 25 18:20:40 EST 1997

In a previous article, jorge2 at (Phil Geis) says:

>Lynn Gerber wrote:
>> There is a bit of controversy at our laboratory as to the length of time a
>> culture for group A beta strep should be incubated.  We are using a
>> selective strep media which inhibits much of the normal flora.  The
>> controversy is whether the negative plates should be kept for more than 24
>> hours.
>Does Bailey and Scott refer here to selective media?  Why is realization
>of Gp. A strep so difficult that you need selective medium?

To the first question - We incubated ours 2 days; enough were positive the
2nd day to warrant a 2-day incubation period.

To the 2nd question - We increased our recovery when we added an SXT plate.
Many grew on the selective plate only.

Carolyn Locy
Phoenix, AZ

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