Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Immuno-Sero LAB > Widal Test > Flashcards

Widal Test Flashcards

1
Q

Typhoid fever
Causative agent:

A

Salmonella enterica serotype typhi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

• Paratyphoid fever
• Causative agent:

A

Salmonella enterica serotype paratyphi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

CAUSATIVE AGENT
ENTERIC FEVER
Family:

A

Enterobacteriaceae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Characteristics
Gram stain…
Motility…
Oxidase…
TSI:…
LF?..
Agar…

A

Gram negative bacilli

Motile

(-)

K/A, G (-), H2S (+)

Non-lactose

Colorless fermenter/ colonies on MacConkey agar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

MODE OF TRANSMISSION
TYPHOID FEVER

Through food, drinks, and water that have been contaminated by sewage

Through food that has been rinsed
in contaminated water and then eaten

Through food that has been touched by a person who did not wash their hands after using the bathroom or changing a diaper

A

Fecal-oral route

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

SIGNS AND SYMPTOMS
TYPHOID FEVER
•______ is common.

• People can have other symptoms, including: WSHCCL

• Some people get a….

A

Fever

• Weakness
• Stomach pain invade vall westine
• Headache
• Constipation or diarrhea
• Cough
• Loss of appetite

rash with flat, rose-colored spots.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

_____less severe

A

Paratyphoid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Antigens of Salmonella typhi

A

H
O
Vi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Antigens of paratyphi

A

O
H

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

•
Flagellin/Flagellar antigen
•
Cell wall/Somatic antigen
•
Capsular polysaccharide
Important for immune evasion and intracellular invasion

A

H antigen

O antigen

Vi antigen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Salmonella paratyphi

H antigen

O antigen

A

Flagellin/Flagellar antigen

Cell wall/Somatic antigen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Paratyphi

Additional antigens:
• S. paratyphi A:
• S. paratyphi B:

A

A

B

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

• A serological test used for over a century to help diagnose typhoid fever.

A

WIDAL TEST

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

WIDAL TEST

• It was developed in 1896 by….

A

Georges-Fernand-Isidor Widal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Widest test

• The test works by detecting antibodies in patient’s serum that are specific to the antigens of_______, the bacterium that causes typhoid fever.

A

Salmonella typhi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

PRINCIPLE
WIDAL TEST

A

• Direct agglutination

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

The test uses suspensions of killed Salmonella typhi bacteria treated to retain specific antigens, namely the O (somatic) and H (flagellar) antigens.

A

Antigens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Direct agglutination
• Antigens
The test uses suspensions of killed Salmonella typhi bacteria treated to retain specific antigens, namely the

A

O (somatic) antigens
H (flagellar) antigens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

• Serum
• A sample of the patient’s blood is taken, and the serum, the liquid portion containing____ against O and H antigens, is separated.

A

antibodies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

• Observation and Interpretation

Presence of agglutination:
Absence of agglutination:

A

Positive

Negative

21
Q

INTRODUCTION
WIDAL TEST
_______ (type of test)
• The correlation of test results with typical signs, symptoms, and patient’s history should be taken into account before arriving at the final diagnosis.

• The test is standardized in such a way that they can be used for____ or ____ technique

A

Screening test

slide or tube technique

22
Q

Widal Test

• An undiluted serum is used in___ test.
• It is simple, rapid, and convenient screening test.

A

slide

23
Q

Widal test

• In doubtful cases, it is recommended to perform the_____ technique for obtaining a conclusive result.
• A marked rise in the titer to one serotype (______) suggests infection.

• Diagnostically, a rising antibody titer of at least_____ (two tube difference) is considered more significant than a single test.

A

tube

above 1:80

four-fold

24
Q

WIDAL TEST

ADVANTAGES

SIM

A

• Relatively simple to perform
• Relatively inexpensive
• Rapid and useful for monitoring the extent of an outbreak

25
Q

WIDAL TEST

DISADVANTAGES

NLILDN

A

• Non-specific, Cross-reactivity
• Lack of standardization
• Influence of prior exposure
• Limited diagnostic value of a single
test
• Difficulty in interpreting results
• Not as accurate as bacterial culture

26
Q

Widal test

False negatives: (3)

A

First week of infection
hyperproteinemia
immune deficiencies

27
Q

Widal test kit containing Salmonella antigens

A

O-antigen of Salmonella Typhi
H-antigen of Salmonella Typhi
AH-antigen of Salmonella Paratyphi A
BH-antigen of Salmonella Paratyphi B

28
Q

Color

O-antigen of Salmonella Typhi

A

Blue

29
Q

Color

H-antigen of Salmonella Typhi

A

Red

30
Q

Color

AH-antigen of Salmonella Paratyphi A

A

Yellow

31
Q

Color

BH-antigen of Salmonella Paratyphi B

A

Green

32
Q

TEST KIT: CONTROLS
WIDAL TEST

POSITIVE CONTROL

Contains ready to use standardized ____ antiserum with ______ having specific reactivity towards:

• S. typhi O and H antigens
• S. paratyphi AH and BH antigens
• S. paratyphi AO and BO antigens
• S. paratyphi CO and CH antigens
• Useful in the validation of the performance of Widal reagents.

A

goat antiserum with polyspecific antibodies

33
Q

TEST KIT: CONTROLS
WIDAL TEST

Contains no antibodies against
the specific bacteria.

A

NEGATIVE CONTROL

34
Q

TEST KIT: CONTROLS WIDAL TEST
• Notes:
• A ______ and ______should be run with each test.
• If the reagent fails to agglutinate with the positive control, or does agglutinate with the negative control, it should be_____.

A

positive and negative control

discarded

35
Q

TEST KIT: REAGENT WIDAL TEST

The kit contains antigen suspensions of_____ and were stained to
enhance the reading of agglutination tests.

The blue stained antigens are specific to the_______, while the red stained antigens are specific to the_______.

A

killed bacteria

somatic antigens (O-Ag)

flagellar antigens (H-Ag)

36
Q

TEST KIT: REAGENT WIDAL TEST

• Types of Antigens used in Widal Test:
________: the thermolabile flagellar antigen

_______: thermostable somatic antigen

A

“H” (Hauch) antigen

“O” (Ohne) antigen

37
Q

SAMPLE
WIDAL TEST

No special preparation of the patient is needed : Clean and dry glassware free from detergents must be used for sample collection.

• ______sample is preferred.
• Do not use hemolyzed samples, turbid,
contaminated or inactivated serum.
• In case of delay the sample should be stored at _____and away from____
• Test should be performed within _____of sample collection.

A

Fresh serum

2-8°C ; direct sunlight

24 hrs.

38
Q

PROCEDURE
WIDAL TEST
• Storage and Stability

• All reagents are stable till expiry date as mentioned on the label of the kit, only when maintained at 2-8°C away from sunlight.
Do not_____.

Precautions before testing

Bring all reagents and samples to
______before use
Shake all the antigens thoroughly
before use.

A

freeze

room temperature

39
Q

PROCEDURE
RAPID SLIDE TEST (SCREENING)
1. Clean the glass slide provided in the kit and wipe.

  1. Place one drop of undiluted serum to be tested in each of the first four circles (1-4).
  2. Add one drop of antigen ___,___,____,____in circles 1, 2, 3, 4 respectively.
  3. Mix the contents of each circle with separate stick and spread to fill the entire circle area.
  4. Rock the slide for ____and observe PC” for agglutination.
  5. If agglutination is visible within one minute then proceed for_____
A

O, H, A(H) and B(H)

one minute

quantitative estimation.

40
Q

PROCEDURE
RAPID SLIDE TEST (SCREENING)
INTERPRETATION

• Valid result
Agglutination with____ control
No agglutination with____ control.

• Negative result
No agglutination up to _____indicates the absence of corresponding antibodies.

• Positive result
Agglutination ______indicates presence of corresponding antibodies.
Proceed for ______for determination of antibody titer.

• Do not observe result after_____

A

positive; negative

one minute

within one minute

semi-quantitative slide or tube technique

one minute

41
Q

is the highest dilution observed in rapid slide screening test which gives visible agglutination.

A

Titer

42
Q

PROCEDURE
QUANTITATIVE SLIDE TEST
• To each of the above circles, add one drop of the appropriate antigen, which gives agglutination in the screening slide test
• Mix the contents of each circle separately and spread it in the entire circle.
• Rotate the slide by hand or on a mechanical rotator at 100 r.p.m. for 1
minute.
• Observe for agglutination in any of the circles
• A diagnostic titer of_____ suggests positive reaction.

A

1:80

43
Q

• NOTE:
• The lowest volume of serum which shows clear agglutination indicates the cut-off level of the positive test and the corresponding antibody titer as seen on the table.

A
44
Q

In non vaccinated persons the titer as high as 1: 80 between _____day of fever is of diagnostic value and the same titer increases gradually during subsequent period.

A

7th or 10th

45
Q

In vaccinated persons the question of anamnestic response should always be borne in mind and ‘____’ titer should not be taken into account for the purpose of diagnosis unless there is a rising titer of ‘H’ in subsequent period.

A

H

46
Q

• The Widal test has a very low specificity, less sensitive, confusing and difficult to interpret for the diagnosis of typhoid fever, because cross-agglutinating antibodies remaining from past infections with related salmonella
serotypes give false-positive results.

A

True

47
Q

• While more specific tests are now available like_____\, but the Widal test is still considered useful in diagnosing typhoid fever in developing countries because of its low cost, and it remains in use in many areas throughout the world.

A

Typhidot Tests

48
Q

• While more specific tests are now available like_____\, but the Widal test is still considered useful in diagnosing typhoid fever in developing countries because of its low cost, and it remains in use in many areas throughout the world.

A

Typhidot Tests

Immuno-Sero LAB (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions