Vibrio cholerae Rapid Diagnostic Test (RDT): Introduction, Principle, Test

Vibrio cholerae Rapid Diagnostic Test (RDT): Introduction, Principle, Test Procedure, Result Interpretation

Introduction of Vibrio cholerae Rapid Diagnostic Test (RDT)

Vibrio choleare is a Gram-negative, highly motile curved rod with a single polar flagellum and can tolerate alkaline media that kill most intestinal commensals, but it is sensitive to acid. It is a causative agent of cholera. Two serogroups of this organism are responsible for epidemic cholera and they are serogroup O1 and serogroup O139 (O139 is found only in Asia and is also called Bengal strain). This ‘Vibrio cholerae Rapid Diagnostic Test (RDT)’ is useful to find out both serogroups within an hour even in an ordinary laboratory setup. It is an Immunochromatographic One Step Rapid Visual Test for Vibrio Cholerae and it is also called dipstick test.

Principle of Vibrio cholerae Rapid Diagnostic Test (RDT)

It works on the principle of lateral flow immunochromatographic assay.

Requirements of Vibrio cholerae Rapid Diagnostic Test (RDT)

Kit Contents:
√Pouches containing a dipstick and a desiccant
√Reaction buffer (1 ml) i.e. sample processing vial
√Disposable plastic droppers
√Test tubes
√Test tube stand
√Instruction for uses (IFU)
Extra we need-

Waste bin for biohazard Waste or disposable waste bag
Gloves
Timer
APW vials ( for cultivation)
Sterile pipette for alkaline peptone water (APW) procedure
Specimen: Stool

Test Procedure of Vibrio cholerae Rapid Diagnostic Test (RDT)

Wear appropriate personal protective equipment while performing this test.
Label a 5 ml test tube with the patient identifier.
Unscrew the sample processing vial and add sample.
For solid, semisolid, or viscous stool, use the sampling stick to collect a small portion of stool from two or more areas in the sample and insert it in the sample processing vial.
For liquid stool, use a transfer pipette to add 2 drops of sample to the sample processing vial.
Tightly recap sample processing vial and shake to mix contents.
Break the outer end of the cap from the sample processing vial.
Dispense 4 drops of processed sample into labeled 5 ml test tube.
Carefully open aluminum pouch along a perforated line.
Label top of the dipstick with the patient identifier.
Place the dipstick in the test tube with the arrows facing down.
Wait 15-30 minutes, remove the dipstick and read the result.

Result Interpretation of Vibrio cholerae Rapid Diagnostic Test (RDT)

Vibrio cholerae O139 detected: Pinkish red bands at 0139 line and control region only

Vibrio cholerae O1 detected: Pinkish red bands at O1 line and control line only

Both Vibrio cholerae O1 and O139 detected: Bands in all three lines

Vibrio cholerae O1 and O139 not detected: Only on the band at the control line

Invalid results: No band at all or band/s other than the control line

Key Notes on Dipstick test for Vibrio cholerae

“Stab stool” but do not “scoop” to avoid picking up particulate matter that may clog the dipstick membrane.
Inspect contents and remember-Only touch the top of the dipstick.
Check dipstick from damage. e.g., no tears, splits, discoloration
Ensure the pouch contains a desiccant that has not changed white in color and discards dipstick if damaged, or if desiccant is missing or changed to white in color.
Confirm the end of the dipstick (“the dipping area”) is submerged in the processed sample and the arrows should remain above the level of the sample.
The target molecule for this dipstick test is a biomarker for Vibrio cholerae O1 and O139 (test will distinguish O1 from O139): LipoPolySaccharide (LPS) (O antigen).
Place all waste in a double-lined plastic bag labeled “Biohazard.”
Analytical sensitivity and specificity are ≥ 95% and 100 % whereas clinical sensitivity and specificity ≥ are 90%, and 93.00%
In case of an invalid result, verify the test procedure and repeat the test with a new testing dipstick.

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