Follow routine procedures for optimal collection and handling of fresh fecal specimens for parasitology.
2. Run a QC sample with each batch of patient tests as in procedure below.
3. As a positive control, Chek-Stix is used; the development of a green, yellow, or orange color with a yellow or red precipitate is considered a positive result.
4. As a negative control, 0.5 ml of deionized water is used; blue color is considered a negative result.
5. Record all QC results. If the QC results are unacceptable, the test must be repeated and documented on the corrective action sheet.
Procedure for Quantitation of Reducing Substances (Clinitest)
1. All testing on clinical specimens should be performed in a biological safety cabinet by personnel wearing gloves and a laboratory coat.
2. Add 1 volume of stool to 2 volumes of deionized water, and mix thoroughly.
3. Using a disposable transfer pipette, transfer 15 drops of this suspension into a clean test tube.
4. Drop one Clinitest tablet reagent into the test tube.
5. Observe the reaction. Do not shake the tube while the chemical reaction is occurring.
6. Wait 15 s after the reaction stops, then gently shake contents to mix.
7. Compare the color of the liquid to the color chart in the package insert of the Clinitest tablet reagent (Fig. 4.11).
8. Discard supplies in appropriate biohazard containers.
Results and Patient Reports for Quantitation of Reducing Substances (Clinitest)
1. Negative: clear to cloudy blue color
2. Positive: compare the liquid color to the color chart that comes with the tablets, and grade the degree of color development to the color chart (trace, 1+, 2+, 3+, or 4+). These results equate to the grams per deciliter of the reducing substance present per sample. The colors range from blue through green through yellow/orange to orange (negative to 4+).
3. Positive: report as Trace (0.25 g/dl), 1+ (0.5 g/dl), 2+ (0.75 g/dl), 3+ (1.0 g/dl), or 4+ (equal to or greater than 2 g/dl)
Example: 1+ (0.5 g/dl)
4. Negative
Example: Negative
Procedure Limitations for Quantitation of Reducing Substances (Clinitest)
1. Clinitest is not specific for glucose and reacts with any reducing substance in stool, including lactose, fructose, galactose, and pentoses.
2. Interfering substances may affect the results. These include salicylates, penicillin, large quantities of ascorbic acid, nalidixic acid, and cephalosporins.
3. Failure to observe the reaction at all times may lead to erroneously low results if reducing substances are present in large amounts. If more than 2% sugar is present, a rapid color change may occur during boiling, causing the color to pass rapidly through bright orange to a dark brown or greenish brown.
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