Bacterial Identification Assays

Yersinia yersinia at CYBERNEX.NET
Fri Jun 13 11:20:05 EST 1997


Jim Campanella writes,

<I teach a laboratory class in bacteriology for undergraduates. Near the  
end of the class, I have them doing identifications of bacterial unknowns 
 using the standard "traditional" methods that we all learned. After they 
were done with their initial identifications last year, I had them use 
the  Biolog plate system to do quick re-identifications using modern 
laboratory methods along with computer analysis. My problem is that I was 
very unhappy with the Biolog system; it was unable to clearly identify 
some bacterial strains that the students named easily using the older 
morpho/physiological methods. My question is: does anyone have any 
recommendations for more accurate test systems that I can have my 
students perform for bacterial identification? Does any company make 
anything more accurate then Biolog plates or is that the height of 
technology?>

Bio-Merieux makes the Vitek, which I'm personally fond of. That company 
also makes API strips, which are probably cheaper to buy, but I like the 
Vitek better than the API strips. I've never used Biolog myself, though, 
but recently I interviewed for a microbiology position at a contract 
testing lab where they used Biolog. My interviewer said he thought that 
the Biolog had the same accuracy as the Vitek, the difference between 
them being that Biolog identifies the organism based on carbon source 
utilization, whereas Vitek uses biochemical tests. Both Vitek and Biolog 
are pretty popular in the "modern laboratory environment" - in my 
observation, Vitek is a little more popular of the two.

If I may mention it, though - in spite of my enthusiasm for the Vitek, 
even that doesn't give clear ID's 100% of the time. And sometimes, it 
does give what appear to be clearcut ID's, until you remember what you 
had on the plate, i.e., what it looked like, where you isolated it from, 
what selective media it grew on, etc., so the ID doesn't make much sense. 
So keep on teaching your "old fashioned" bacteriological methods, because 
even with only five years of experience working in professional micro 
labs, I can tell you that there will be times your students will need 
them.  :-) In the "modern laboratory," identification systems should 
really be used to confirm what you the scientist, based on "traditional" 
knowledge, your estimate of the organism ID, rather than simply taking 
the printout of a Vitek as the "word of gospel" without question.

Infectionately,
Yersinia.

Mycelium is Yourcelium.  :-)




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