Staphylococcus aureus

Dilworth bactitech at hortonsbay.com
Sat Feb 24 00:55:53 EST 2001

We use Staphaurex (a white liquid), which I think is made by Murex (gee,
I use it every day and can't remember the manufacturer) and it is by far
the best slide reagent I've ever used.  We tried Staphyloslide (a blue
reagent) when we were backordered with Staphaurex and it was much more
difficult to read, and no one liked it.

Are you using the official shiny black cards that are supposed to be
used with this reagent?  There are six circles on a card. It is
important that these cards be used with the reagent.  Are you mixing the
reagent before use?  The latex particles tend to go to the bottom after
sitting, so you need to tip the bottle a few times to resuspend them,
and also let them get to room temperature before using.

Are you sure these are Staphylococci?  Are they catalase positive gram
positive cocci?  Sometimes you can get weird reactions with
diphtheroids.  As I said, we have many MRSA isolates and have had no
problems with them.  Are these isolates from one particular patient?  If
the patient has been treated with many antibiotics, or if the organism
is somewhat mucoid, you sometimes need the tube coagulase to confirm, as
the slide just won't work.  

The gold standard test is a tube coagulase which requires overnight
incubation and utilizes coagulase plasma.  We put 0.5 ml in a small
tube, inoculate fresh growth of the organism, incubate in a 35 degree C
heat block for four hours, then at room temperature overnight on the
bench top.  We also run positive and negative controls with each batch.

Did you run QC on the reagents on receipt?  Were the reactions OK?  Are
you storing the reagent in a refrigerator?

That's about all I can think of to troubleshoot your problem.  As I
don't know how much micro you do, I've probably asked some obvious
questions. Hope I didn't offend anyone.....

Judy Dilworth, M.T. (ASCP)
news wrote:
> I work in a medical microbiology labor
> I have a problem with koagulase reaction
> Can somebody help me????
> we work with a koagulase -reagens from the firma
> murex
> but in the last time we have more and more false negative
> reations.
> Can give me some tips or know someone better products?
> Especially  with MRSA we have problems and with "normal" resistant
> Staphylococci too
> thx
> Sorry of my bad English ( isn't my mother- language)

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