Cold reagents

could give false negative results

All reagents must be brought to room temperature before use

6. The tube is shaken very vigorously while observing for agglutination

Shake the tube gently after incubation and observe for agglutination.

‘O’ antigen will show coarse, compact, granular agglutination whereas

‘H’ antigen will show large, loose, flocculant agglutination

7.  Insufficient reagent present in the vial Ensure sufficient reagent is present in the vial before retrieving

Problem: False negative results

RAPID TEST FOR DETECTION IGM ANTIBOD- IES TO S. TYPHI IN SERUM/PLASMA/WHOLE

BLOOD (DEVICE) ENTEROCHECK – WB

(Courtesy: Tulip Group of Companies)

Enterocheck-WB

Enterocheck-WB is a rapid, qualitative, sandwich immunoassay for the detection of IgM antibodies to S.Typhi in

human serum/plasma or whole blood specimen.

Summary

A febrile condition, Typhoid fever, is a bacterial

infection caused by Salmonella serotypes including S.

Typhi, S. paratyphi A, S. paratyphi B and Salmonella

sendai. The symptoms of the illness include high

fever, headache, abdominal pain, constipation and

appearance of skin rashes. Accurate diagnosis of

typhoid fever at an early stage is not only important

for etiological diagnosis but to identify and treat the

potential carriers and prevent acute typhoid fever

Serology/Immunology 633

outbreaks. The conventional WIDAL Test usually

detects antibodies to S. typhi in the patient serum from

the second week of onset of symptoms. However, the

detection may be earlier if specific IgM antibodies

are detected instead of IgG or both IgG and IgM.

Enterocheck-WB qualitatively detects the presence of

IgM class of antibodies to Lypopolysaccharide (LPS)

specific to S. typhi in human serum/plasma or whole

blood specimens.

Principle

Enterocheck-WB utilizes the principle of Immuno -

chromatography, a unique two-site immunoassay on a

nitrocellulose membrane. The conjugate padcontains

two components – Anti-human IgM antibody conjugated

to colloidal gold and rabbit IgG conjugated to colloidal

gold. As the test specimen flows through the membrane test assembly, the highly specific anti-human IgM

antibody-colloidal gold conjugate complexes with the S.

typhi specific IgM antibodies in the specimen and travels

on the membrane due to capillary action alongwith the

rabit IgG-colloidal gold conjugate. This complex moves

further on the membrane to the test region (T) where it is

immobilized by the S. typhi specific LPS antigen coated

on the membrane leading to formation of a pink to deep

purple colored band. The absence of this colored band in

the test region indicates a negative test result.

The unreacted conjugate and unbound complex, if any,

move further on the membrane and are subsequently

immobilized by the anti-rabbit antibodies coated on the

membrane at the control region (C), forming a pink to

deep purple colored band. This control band acts as a

procedural control and serves to validate the results.

Reagents and Materials Supplied

Each kit contains.

A. Individual pouches, each containing a -

1. Membrane test assembly: Membrane assembly

pre-dispensed with anti Human IgM–colloidal gold

conjugate, S. typhi LPS antigen and anti-rabbit

antiserum coated at the respective regions.

2. Desiccant pouch

B. Sample Running Buffer

C. Package Insert.

Optional Material Required

5 µL precision pipette.

Storage and Stability

The sealed pouches in the test kit and the kit components

may be stored between 4–30°C for the duration of the shelf

life as indicated on the pouch.

Note

1. Forin vitro diagnostic use only. Not for medicinal use.

2. Do not use beyond expiry date.

3. Read the instructions carefully before performing the

test.

4. Handle all specimen as if potentially infectious.

5. Follow standard biosafety guidelines for handling and

disposal potentially infectious material.

6. If desiccant color at the point of opening the pouch

has turned from blue to pink or colorless, another test

device must be run.

Specimen Collection and Preparation

1. Enterocheck-WB uses human serum/plasma/whole

blood as specimen.

2. No special preparation of the patient is necessary

prior to specimen collection by approved techniques.

3. For whole blood, collect blood with a suitable

anticoagulant such as EDTA or Heparin or Oxalate

and use the freshly collected blood.

4. Whole blood should be used immediately and

should not be frozen.

5. Though fresh specimen is preferable, incase of delay

in testing, it may be stored at 2–8°C for maximum up

to 24 hours.

6. If serum is to be used as specimen, allow blood to

clot completely. Centrifuge to obtain clear serum.

7. Repeated freezing and thawing of the specimen

should be avoided.

8. Do not use turbid, lipemic and hemolyzed serum/

plasma.