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Journal of Clinical Microbiology, July 1998, p. 1974-1976, Vol. 36, No. 7
Department of Pathology and Laboratory
Medicine, Clinical Microbiology, University of California at Los
Angeles Medical Center, Los Angeles, California 90095-1713
Received 6 November 1997/Returned for modification 24 February
1998/Accepted 15 April 1998
As a result of disposal problems related to the use of mercury
compounds, many laboratories have switched from mercuric chloride-based Schaudinn's and polyvinyl alcohol (PVA) stool preservatives to other,
non-mercury-based preservatives. A comparison of organism recoveries and morphologies of the intestinal protozoa was undertaken with PVA containing the EcoFix zinc-based Schaudinn's preservative (Meridian Diagnostics, Inc.); both Wheatley's modification of Gomori's trichrome stain (WT) and EcoStain (ES) were used to stain 51 human fecal specimens. Morphology, clarity of nuclear and cytoplasmic detail, overall color differences, and the ease or difficulty in
detecting intestinal protozoa in fecal debris were assessed for the two
permanent stained smears. Overall, organism morphology of the
intestinal protozoa stained with WT and that of protozoa stained with
ES were not equal in nuclear and cytoplasmic detail or range of color.
However, the same organisms were identified in stained fecal
smears with either WT or ES, with the exception of situations in which
organism numbers were characterized as rare. Included were 67 protozoan
challenges (number of organisms): Entamoeba
histolytica-Entamoeba dispar (5), Entamoeba coli (9), Entamoeba hartmanni (6), Endolimax nana (12),
Iodamoeba bütschlii (8), Blastocystis
hominis (19), Giardia lamblia (6), Dientamoeba fragilis (2), yeast (2), and leukocytes (2). Five specimens were negative for parasites but contained fecal debris that was compared for
morphologic detail and color range. The ES produces a more gray-green
monotone with very little pink or red tone; contrast among the various
colors is less than that seen with WT. Stain intensity for all
organisms was acceptable, and there were no problems with stain
deposition. The quality of the protozoan morphology with ES was often
comparable to that with WT (36 of 67 [53.7%]) and, in some cases,
better (24 of 67 [35.8%]). Organisms on the WT-stained smear
exhibited better morphology in a few instances (4 of 67 [6%]), and
in three instances, there were discrepant organism numbers.
0095-1137/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Evaluation of Intestinal Protozoan Morphology in
Human Fecal Specimens Preserved in EcoFix: Comparison of
Wheatley's Trichrome Stain and EcoStain
*
Corresponding author. Mailing address: Department of
Pathology and Laboratory Medicine, UCLA Medical Center (171315), 10833 Le Conte Ave., Los Angeles, CA 90095-1713. Phone: (310) 794-2752. Fax:
(310) 794-2765. E-mail: lgarcia1{at}ucla.edu.
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