Comparison of Polyvinyl Alcohol Fixative with Three Less Hazardous Fixatives for Detection and Identification of Intestinal Parasites

Abstract

Polyvinyl alcohol (PVA) containing the fixative mercuric chloride is considered the “gold standard” for the fixation of ova and parasites in the preparation of permanently stained smears of stool specimens. However, mercuric chloride is potentially hazardous to laboratory personnel and presents disposal problems. We compared three new alternative, nontoxic fixatives with PVA, analyzing ease of sample preparation and quality of smears. Sixty-eight fresh stool specimens were divided into aliquots and placed in each of four different fixatives: PARASAFE (PS) (Scientific Devices Laboratory, Inc., Des Plaines, Ill.), ECOFIX (EC) (Meridian Diagnostics, Inc., Cincinnati, Ohio), Proto-Fix (PF) (Alpha-Tec Systems, Inc., Vancouver, Wash.), and low-viscosity PVA fixative (PVA) (Meridian). Specimens were processed and stained according to each manufacturer's directions. Parasites were found in 31 of 68 slide preparations with PVA, 31 with PF, 30 with EC, and 30 with PS. Blastocystis hominis andIodamoeba bütschlii were preserved in a readily identifiable state by all methods of fixation. However, some parasites were more easily identified with some of the fixatives because of differences in parasite distortion. For example, Entamoeba histolytica (Entamoeba dispar) was detected in 13 stools fixed with PF, 7 with PVA, and 6 with EC but none with PS. Likewise, Chilomastix mesnili was identified in 13 specimens fixed with PF, 8 with EC, and 5 with PVA but only 1 with PS, while Entamoeba coli was seen much less frequently with PS than with the other three fixatives. A dirty background was observed in 41% of specimens prepared with PS, whereas background quality was acceptable with other fixatives. Sample preparation was most rapid with PS, although the EC method involved the fewest steps. In conclusion, PVA and PF produced the least parasite distortion, while PS proved unsatisfactory for the identification of E. histolytica,E. coli, and C. mesnili. Both PF and EC appear to be acceptable, environmentally safe substitutes for PVA.

Gastrointestinal symbionts of chimpanzees in Cantanhez National Park, guinea‐bissau with respect to habitat fragmentation

“…Only fresh samples were collected (from their inner part to avoid soil contamination), any potentially rain‐ “washed” or old (>12 hr) samples were discarded. Approximately 5 g of each sample was immediately fixed in a 13 ml single vial tube of PROTOfix™ CLR (Alpha‐tech‐Systems, Inc., Vancouver, WA) according with the manufacturer's instructions [Jensen et al, ] and stored at room temperature until they were shipped under international permits to the Department of Pathology and Parasitology of the Veterinary and Pharmaceutical University, Brno, Czech Republic.…”

In vitro culture of Blastocystis hominis in three liquid media and its usefulness in the diagnosis of blastocystosis

“…Several studies have indicated that some less hazardous mercury-free fixatives might be substitutions for traditional fixing agents. [16][17][18][19] The objective of the present study was to determine whether in vitro culture could be another totally environmentally safe method of choice for diagnosing B. hominis infection for clinical and epidemiological purposes. Growth characteristics of B. hominis in vitro in three commercially available monophase liquid media, Roswell Park Memorial Institute (RPMI) 1640 medium (10.4 g, Gibco BRL), 199 Medium (9.5 g, Gibco BRL), and Dulbecco's modified Eagle's medium (DMEM; 13.4 g, Gibco BRL), were observed and compared.…”

The Transmission Pattern of Amoebiasis in Bale Zone, South East Ethiopia

“…Then, all stool samples kept in dry universal bottles were sent immediately to the Delomena Hospital Laboratory, Mena town, Ethiopia, for further studies. Ritchie's fecal concentration technique (Ritchie, 1948) and polyvinyl alcohol fixation of stools were carried out to obtain maximum sensitivity (Jensen et al, 2000). The fresh stool specimen was preserved with polyvinyl alcohol, and kept cool (4°C).…”