Q1. What is TOTAL- FIX ?
A. TOTAL- FIX is a FIXative with a proprietary formula, it is similar to UniFIX and Zinc PVA (Z- PVA ), a commonly used fixative that has been commercially available and used in many laboratories since 1992.
Q2. What is PVA ?
A. PVA stands for polyvinyl alcohol, a plastic powder/resin that is incorporated into the fixative (Schaudinn’s or other fixatives such as Z- PVA ) and serves as an adhesive to “glue” the stool material onto the slide. PVA itself has no preservation capability.
Q3. Since PVA is used to “glue” the stool onto the slide prior to permanent staining, how does the material stick to the glass slide?
A. The TOTAL- FIX user can add some albumin to the slide prior to preparation of the stool smear for staining. However, if the stool smear is thoroughly dry prior to staining, albumin will not be necessary.
Q4 How long should the slides prepared from TOTAL- FIX be dried prior to processing for routine staining (trichrome or iron-hematoxylin)?
A. Spread the sample over the slide to prepare a thin smear which varies in thickness (routine preparation of slides – no changes required). Allow to dry overnight at room temperature or for several hours (minimum of 30 min; 60 min if slide is thicker) in a 37oC incubator or slide warmer (the smear will appear opaque when dry). Many labs routinely prepare their smears and then place the smears on a tray in the incubator (37ºC) for 60 min to dry. The fecal smears can be left longer in the incubator with no damage at all to the slides. Do not use a heating block; the higher temperature for most heating blocks will be detrimental to any organisms (protozoa, coccidia, microsporidia) present.
Q5. What should Giardia lamblia and other protozoa look like when stained from normal patient clinical specimens (no lag time between specimen passage and fixation)?
A. Organism morphology should appear no different from organisms preserved in Z- PVA , with good overall morphology for trophozoites, cysts (routine trichrome or iron-hematoxylin), coccidian oocysts (modified acid-fast stains), and microsporidial spores (modified Trichrome).