9. Do not use hemolyzed, clotted, contaminated,

viscous/turbid specimens.

10. Specimen containing precipitates or particulate

matter must be centrifuged and the clear supernatant

only used for testing.

11. Refrigerated specimens must be brought to room

temperature prior to testing.

Testing Procedure and Interpretation of Results

1. Bring the kit components of Enterocheck-WB device

to room temperature before testing.

2. Open a foil pouch by tearing along the “notch”.

634 Concise Book of Medical Laboratory Technology: Methods and Interpretations 3. Remove the testing device and the specimen dropper.

Once opened, device must be used immediately.

4. Label the device with specimen identity.

5. Place the testing device on a flat horizontal surface.

6. Carefully dispense 5 µL of whole blood/serum

/plasma into the specimen port “A” using a

micropipette or the sample loop provided. Dip the

sample loop in the sample container and blot the

sample in the sample port “A”.

7. After 30 sec, add five drops of sample running buffer

into the port “B”.

8. Observe the development of visible colored band at

Test window (T).

9. Positive results may be observed within 15 minutes,

depending on the concentration of IgM antibodies

in the tested specimen.

10. The test should be considered invalid if the control

band does not appear. Repeat test with a new

Enterocheck-WB device.

 Negative

 If IgM antibodies to S. typhi are not present, only one

colored band at Control (C) would appear.

 Positive

 If IgM antibodies to S. typhi are not present, two

colored bands appear at Test (T) and Control (C)

regions. The intensity of the test band may be more

or less than the control band, depending upon the

concentration of IgM antibodies in specimen.

 Invalid

 The test is invalid if the Control band is not visible at

15 minutes. Verify the test procedure and repeat the

test with a new Enterocheck-WB device.

11. The test should be considered invalid if neither the

control band ‘C’ nor the test band ‘T’ appears. Repeat

the test with a new device.

Remarks

1. In the studies it has been reported that IgM antibodies

to S. typhi persist for about 4 months post infection.

Therefore, results within four months from an endemic

area should be interpreted with caution.

2. The following chart would explain the IgM seroresponse

in S. typhi infected subjects after onset of fever.

Detectable IgM Response

Onset of fever Percent positive

4–6 days

6–9 days

> 9 days

43.50%

92.90%

100%

3. A negative result, i.e. the absence of detectable IgM

antibody does not rule out recent or current infection.

However, if S.typhi infection is still suspected, obtain a

second specimen 5–7 days later and repeat the testing.

4. Specific IgG may compete with the IgM for sites and

may result in a false negative. Conversely, rheumatoid

factor in the presence of specific IgG may result in a

false positive reaction.

5. The membrane is laminated with an adhesive tape to

prevent surface evaporation. Air pockets or patches

may appear, which do not interfere with the test

results. Presence of a band at the test region even if

low in intensity or formation is a positive result.

6. The deliberate slow reaction kinetics of EnterocheckWB is designed to maximize and enhance reaction

time between sample capture and tracer elements to

improve test sensitivity.

7. Most positive results develop within 15 minutes.

However, certain sera sample may take a longer time

to flow. Therefore, negatives should be confirmed

only at 30 minutes. Do not read results after 30

minutes.

8. As with all diagnostic tests, a definitive clinical

diagnosis should not be based on the result of a

single test, but should only be made by the physician

after all clinical and laboratory findings have been

evaluated.

9. Enterocheck-WB should be used as a screening test in

clinically suspected cases only, and its results should

be confirmed by other supplemental method before

taking clinical decisions.

Serology/Immunology 635

SLIDE AND TUBE TEST FOR DETECTION OF

ANTIBODIES TO BRUCELLA ABORTUS/

MELITENSIS BRUCEL A/M

(Courtesy: Tulip Group of Companies)

Summary

Human brucellosis (diurnal, or undulant fever) is a common

febrile illness caused by infection with bacteria of some of

the Brucella species (abortus, melitensis). This undulant

fever is associated with symptoms, which are often variable

and nonspecific with chills, fever, sweats and anorexia. On

exposure, the body responds to this antigenic stimulation by

producing specific antibodies whose titers rise slowly at early

stages and then increases. Specific antibodies to the Brucella

species are detectable a few weeks after exposure and are

of considerable importance in the diagnosis of brucellosis.

Information regarding the titer of antibodies can be obtained

by using specific Tulip Brucel antigen suspensions.

Reagent

The Brucel-A/Brucel-M reagents contain ready-touse standardized, attenuated, stained, smooth specific

antigen suspensions of Brucella having specific reactivity

towards antibodies to Brucella abortus (Brucel-A), and

Brucella melitensis (Brucel-M).

Reagent Storage and Stability

Store the reagent at 2 to 8°C. Do not freeze.

The shelf-life of the reagents is as per the expiry date

mentioned on the reagent vial labels.

Each batch of reagents undergoes rigorous quality

control at various stages of manufacture for its specificity,

sensitivity, and performance.

Principle

The smooth, attenuated, stained Brucella antigen

suspensions are mixed with the patient’s serum. Specific

antibodies to Brucella antigens if present in the patient

serum will react with the antigen suspension to produce

an agglutination reaction. No agglutination indicates the

absence of specific antibodies to Brucella antigens.

Note

1. In vitro diagnostic reagent for laboratory and professional use only. Not for medicinal use.

2. The reagent contains thimerosal 0.01% as preservative.