Why this difference?

Yjgent yjgent at aol.com
Tue Aug 29 20:22:17 EST 2000

Isn't microbiology wonderful! The 1st rule of micro that I teach to new
trainees is that "Every rule in microbiology has an exception - except this
one!" The 2nd thing I teach is that the bacteria are living beings capable of
doing what ever they want whenever they want - they don't read the manuals!

The oxidase tests can be done with 2 different oxidase reagents - one works
better with Gram neg rods and the other works better with Gram neg cocci. In
both cases the reaction should be read in 10 to 15 SECONCDS. There are some
test cards made by Difco, but I never liked them. Also to remember - a metal
needle or loop can cause a positive reaction (except platinum)

The VP test can be done in a kit like the API 20 E or the Microscan ID panel
And it can be done on a broth the "old fashioned" way. Which ever way you do it
follow the instructions for that method - you can't mix them up! The API test
is to be read at 10 minutes, the Microscan is at 20 minutes, the MRVP tube test
can be read between 15 min and up to 1 hour. A positive is a red color at the
time of reading, a clear or weak pink or copper color is negative.
Hope this clears up some things!

>In some mannuals it is mentioned that an oxidase reaction is positive
>if black colour develops on the addition of the reagent...in some
>others they say development of blue colour within 15 minutes is 

John Gentile M(ASCP)                   President - Rhode Island Apple Group
yjgent at aol.com
Microbiologists do it with culture.

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