Ls. Garcia et Ry. Shimizu, EVALUATION OF INTESTINAL PROTOZOAN MORPHOLOGY IN HUMAN FECAL SPECIMENS PRESERVED IN ECOFIX - COMPARISON OF WHEATLEY TRICHROME STAIN AND ECOSTAIN, Journal of clinical microbiology, 36(7), 1998, pp. 1974-1976
As a result of disposal problems related to the use of mercury compoun
ds, many laboratories have switched from mercuric chloride-based Schau
dinn's and polyvinyl alcohol (PVA) stool preservatives to other, non-m
ercury-based preservatives. A comparison of organism recoveries and mo
rphologies of the intestinal protozoa was undertaken with PVA containi
ng the EcoFix zinc-based Schaudinn's preservative (Meridian Diagnostic
s, Inc.); both Wheatley's modification of Gomori's trichrome stain (WT
) and EcoStain (ES) were used to stain 51 human fecal specimens. Morph
ology, clarity of nuclear and cytoplasmic detail, overall color differ
ences, and the ease or difficulty in detecting intestinal protozoa in
fecal debris were assessed for the two permanent stained smears. Overa
ll, organism morphology of the intestinal protozoa stained with UT and
that of protozoa stained with ES were not equal in nuclear and cytopl
asmic detail or range of color, However, the same organisms were ident
ified in stained fecal smears with either WT or ES, with the exception
of situations in which organism numbers were characterized as rare. I
ncluded were 67 protozoan challenges (number of organisms): Entamoeba
histolytica-Entamoeba dispar (5), Entamoeba coli (9), Entamoeba hartma
nni (6), Endolimax nana (12), Iodamoeba butschlii (8), Blastocystis ho
minis (19), Giardia lamblia (6), Dientamoeba fragilis (2), yeast (2),
and leukocytes (2), Five specimens were negative for parasites but con
tained fecal debris that was compared for morphologic detail and color
range. The ES produces a more gray-green monotone with very little pi
nk or red tone; contrast among the various colors is less than that se
en with WT. Stain intensity for all organisms was acceptable, and ther
e were no problems with stain deposition. The quality of the protozoan
morphology with ES was often comparable to that with UT (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 numbe
rs.