Performance of Para-Pak (TM) Ultra ECOFIX (TM) compared with ParaPak (TM) Ultra formalin/mercuric chloride-based polyvinyl alcohol for concentration and permanent stained smears of stool parasites

ECOFIX(TM) is a mercury and formalin-free fecal preservative that can be us ed for concentration of stool specimens and preparation of permanently-stai ned slides. In this study, the standard two-vial ParaPak(TM) Ultra system w as compared with ECOFIX(TM) Ultra for the detection of intestinal parasites . A total of 261 specimens in 92 sets (77 with 3 specimens, 15 with 2 speci mens) were collected in ECOFIX(TM), formalin, and low viscosity polyvinyl a lcohol (LV-PVA). Concentrations were performed from ECOFIX(TM) using Hemo-D e and saline and from formalin using ethyl acetate and formalin. To prepare permanently-stained smears, ECOSTAIN(TM) (a modification of Wheatley's tri chrome stain) was used on ECOFIX(TM) material and Wheatley's trichrome stai n was used on specimens preserved in PVA. A total of 157 protozoa and helmi nths were detected; 132 (84.1%) were recovered in formalin/PVA and 129 (82. 2%) in ECOFIX(TM). fn permanently-stained smears, 139 protozoa were observe d, 116 (83.5%) in PVA-preserved material and 117 (84.2%) in ECOFIX(TM). Fec al concentration yielded 111 parasites (103 protozoa and 8 helminths), of w hich 98 (88.3%) were detected in formalin-fixed stool and 48 (43.2%) in ECO FIX(TM). Significantly fewer ECOFIX(TM)-preserved concentrates were positiv e for Blastocystis hominis (35 versus 15, p-value <0.001) and Endolimax nan a (19 versus 2, p-value <0.001). In conclusion, use of the ECOFIX(TM) Ultra collection device in combination with ECOSTAIN(TM) resulted in largely com parable recovery of enteric parasites to the conventional two-vial ParaPak( TM) Ultra system when both sedimentation-concentration and permanently stai ned smears were performed, and 2-3 specimens per patient were evaluated. (C ) 2000 Elsevier Science Inc. All rights reserved.