title: Performance of para-Pak Ultra ECOFIX compared with Para-Pak Ultra formalin/mercuric chloride-based polyvinyl alcohol for concentration and permanent stained smears of stool parasites.
abstract: ECOFIX is a mercury and formalin-free fecal preservative that can be used for concentration of stool specimens and preparation of permanently-stained slides. In this study, the standard two-vial ParaPak Ultra system was compared with ECOFIX Ultra for the detection of intestinal parasites. A total of 261 specimens in 92 sets (77 with 3 specimens, 15 with 2 specimens) were collected in ECOFIX, formalin, and low viscosity polyvinyl alcohol (LV-PVA). Concentrations were performed from ECOFIX using Hemo-De and saline and from formalin using ethyl acetate and formalin. To prepare permanently-stained smears, ECOSTAIN (a modification of Wheatley's trichrome stain) was used on ECOFIX material and Wheatley's trichrome stain was used on specimens preserved in PVA. A total of 157 protozoa and helminths were detected; 132 (84.1%) were recovered in formalin/PVA and 129 (82.2%) in ECOFIX. In permanently-stained smears, 139 protozoa were observed, 116 (83.5%) in PVA-preserved material and 117 (84.2%) in ECOFIX. Fecal concentration yielded 111 parasites (103 protozoa and 8 helminths), of which 98 (88.3%) were detected in formalin-fixed stool and 48 (43.2%) in ECOFIX. Significantly fewer ECOFIX-preserved concentrates were positive for Blastocystis hominis (35 versus 15, p-value <0.001) and Endolimax nana (19 versus 2, p-value <0.001). In conclusion, use of the ECOFIX Ultra collection device in combination with ECOSTAIN resulted in largely comparable recovery of enteric parasites to the conventional two-vial ParaPak Ultra system when both sedimentation-concentration and permanently stained smears were performed, and 2-3 specimens per patient were evaluated.
authors.affiliation: Microbiology Service, Clinical Pathology Department, Warren Grant Magnuson Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA. dfedorko@nih.gov
authors.forename: D P
authors.initials: DP
authors.lastname: Fedorko
authors.forename: E C
authors.initials: EC
authors.lastname: Williams
authors.forename: N A
authors.initials: NA
authors.lastname: Nelson
authors.forename: T D
authors.initials: TD
authors.lastname: Mazyck
authors.forename: K L
authors.initials: KL
authors.lastname: Hanson
authors.forename: C P
authors.initials: CP
authors.lastname: Cartwright
mesh_terms: D005243:Feces / Q000469:parasitology*; D005557:Formaldehyde; D006373:Helminthiasis / Q000175:diagnosis / Q000469:parasitology*; D008627:Mercuric Chloride; D011142:Polyvinyl Alcohol; D011528:Protozoan Infections / Q000175:diagnosis / Q000469:parasitology*; D011933:Reagent Kits, Diagnostic; D013194:Staining and Labeling / Q000379:methods
chemical_list: D011933:Reagent Kits, Diagnostic; D005557:Formaldehyde; D008627:Mercuric Chloride; D011142:Polyvinyl Alcohol