EVALUATION OF INTESTINAL PROTOZOAN MORPHOLOGY IN HUMAN FECAL SPECIMENS PRESERVED IN ECOFIX - COMPARISON OF WHEATLEY TRICHROME STAIN AND ECOSTAIN

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.