Need Biolog help.

Peter Herman herman at populus.slu.se
Tue Sep 17 23:41:14 EST 1996


Keith (kbiggs at digital.net) wrote:

: We have recently acquired a Biolog microstation, and are having problems 
: getting good clean identifications with gram positive organisms. Has anyone 
: had any similar problems? I have been using both TSA and TSA w blood , and 
: both give equally poor results. Specifically, a colour change occurs in almost 
: all of the wells, making visual ID difficult. Any suggestions? Your help would 
: be greatly appreciated. Keith

In addition to the possible contamination/QC problems already mentioned, 
there is a potential problem with the organism itself.  If you get 
extensive capsule formation, all bets are off!  I have had all 96 wells 
light up with a heavly encapsulated bug.  It seems that if it can't use 
the C source in the well, it metabolizes its capsule.  This results in the 
transfer of electrons to the dye and a false positive for that well. There 
is nothing like coming into the lab, looking at a Biolog plate and seeing 
a positive in the A1 well (water)  :-(

Peter


--
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R. Peter Herman				email	Peter.Herman at mv.slu.se
Sveriges Lantbruksuniversitet		Phone:	+46 18 67 12 20
Inst. f. Markvetenskap			Fax:	+46 18 67 27 95
S750 07 Uppsala, Sweden		
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