Fecal flotations

Judy/Bob Dilworth dilworth at megsinet.net
Mon Mar 15 18:45:45 EST 1999


I agree that new techs sometimes have a hard time with Giardia.  I take
issue, however with your statement that "..... I'm not sure if Med Techs
see
enough parasite cases in routine practice to become truly proficient at
identification of Giardia and Crypto."  We have to pass proficiency
examinations through CAP (College of American Pathologists) in all
phases of O&P procedure, depending upon the level we report out
(complicated).  The labs I've worked in have always done very well,
rarely missing a proficiency, and we were never "out of the ball park." 
If any of our techs has a question on any slide, it immediately becomes
a group effort, measurements are taken, trichromes are compared, etc.
etc.  We do 5-10 O&P procedures/day/5 day work week and probably run
into Giardia 1-2 times/month (midwest rust belt).  We do not perform
that many stains for Cryptosporidium for reasons I enumerated before -
mainly doc has to order these stains. I myself have only ever seen one
patient positive for Cryptosporidium and he was HIV positive (about 5
years ago, and it was specifically ordered by the Infectious Disease
physician). Three of the techs in our lab (myself included) have 15-20
years lab experience, and the others less - if they run into trouble
they ALWAYS come to one of us for an opinion.  I therefore doubt if
we're missing much.  Of course, I can't speak to other laboratories. 
There was talk of just running Giardia antigens and dispensing with
manual O&P preps all together when I was working in a hospital, but this
never came about.  Many hospitals now refuse to perform O&P exams on any
patients that develop diarrhea after three or more days in-house.  As an
independent reference laboratory, we do not have the luxury of dictating
when we will perform these exams, other than limiting specimens to one
per day (because of insurance reimbursements).

Obviously with an animal population you're going to run into a higher
percentage of positives (considering that our neighbor's dog eats his
own you-know-what and our cat catches numerous small rodents this
doesn't surprise me) so you would of course become proficient if you
were seeing a high percentage of positives.  The most positives I ever
saw was right after the fall of Viet Nam in the mid 70's when all of the
"boat people" were arriving in the U.S.  These unfortunately people were
positive for 3-5 different types of parasites at a time.  Not being in a
port city, we midwesterners are somewhat limited in our exposure to
parasites - that's why surveys are so very important.

Judy Dilworth, M.T. (ASCP)
Microbiology since 1974

"Charles T. Faulkner" wrote:
> 
> On Sat, 13 Mar 1999, James L. Mau, Biologist wrote:
> 
> >       Two reasons for going to test methods like ELISA are: 1) cost and 2)to
> >       help eliminate errors in identifying organisms by less skilled eyes. Our
> 
> I think you are right on target with these observations. If a single ELISA
> test can reliably detect Giardia or Cryptosporidium then cost containment
> is a valid argument....



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