Microscan-E. coli/Shigella

Pustule glum at ozemail.com.au
Sat Aug 31 00:43:15 EST 1996

Greetings.  A recent Microscan Technical Bulletin highlighted a problem
of inactive E. coli being misidentified as Shigella.  Have any of the
Vitek users come across this problem?

In our lab we recently had three isolates in three weeks which we think
were inactive E.coli organisms that the Microscan Walkaway identified as
Shigella (high probability).  This is because of the high weighting
placed on tests like Indole, LDC and ONPG.  I have been told by our
local enteric pathogens reference laboratory that some of these
organisms might weakly cross react with S. boydii anti-sera making the
identification even more difficult.

My reaction has been to look at the patient in their clinical context
and to integrate other laboratory results like stool cell counts.  I
have basically sat back on these three because clinically they did not
appear to have shigellosis.  However, one day I might miss a shigellosis
with this approach.

I'd appreciate comments and hints on what I can do.  Please don't
respond by saying I should have a Vitek, we have a contract with
Microscan that cannot be broken for the next few years.

Thanks for your help.


Dr Gary Lum
Director of Microbiology
Royal Darwin Hospital

Microbiologists do it with Culture and Sensitivity
Meet me at my Home page http://www.ozemail.com.au/~glum/index.html

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