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Welcome to Journal club


Welcome to Journal club Dr. Md. Abul Hossain Khan Honorary Trainee Department of microbiology, MMC A Comparative Study of Typhidot and Widal Test in Patients of ... – PowerPoint PPT presentation

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Title: Welcome to Journal club

Welcome to Journal club
  • Dr. Md. Abul Hossain Khan
  • Honorary Trainee
  • Department of microbiology, MMC
  • A Comparative Study of Typhidot and Widal Test
    in Patients of Typhoid Fever

Introduction 1
  • Typhoid fever is a life threatening systemic
    infection occurring in developing areas of the
    world and a major public health problem.
  • Annually at least 16 million new cases of typhoid
    globally and more than 13 million cases in Asia
    and causing more than six lakhs deaths worldwide.
  • Blood culture and widal test are routinely
    employed investigations for diagnosis of typhoid
    fever in all clinical settings.

Introduction 2
  • Widal test has been used in the diagnosis of
    typhoid illness for long time in our country but
    it remains a serological test with a moderate
    sensitivity and specificity.
  • Therefore, a reliable and easy to perform
    serodiagnostic test with a higher sensitivity and
    specificity than widal test is required for rapid
    diagnosis and management of typhoid cases
    reducing morbidity and its complications.

Introduction 3
  • Typhidot is a rapid serological test for the
    diagnosis of typhoid fever.
  • However, its specificity and sensitivity as
    compared to widal test has not been studied so
    far in our region.
  • Few studies conducted in India and other parts of
    Asia have reported encouraging results.
  • In view of this, the present study was conducted
    to know its utility and effectiveness in
    diagnostic yields as compared to widal test in
    this region.

Materials and Methods
  • Typhidot test is a dot ELISA kit.
  • The test is based on the presence of specific IgM
    and IgG antibodies to a specific 50KD OMP antigen
    of the Salmonella typhi.
  • The typhidot test becomes positive within 2-3
    days of infection and separately identifies IgM
    and IgG antibodies.

Interpretation of Typhidot
  • A positive IgM was interpreted clinically as
    acute typhoidal illness
  • While IgM and IgG positive were taken as acute
    typhoidal illness in middle stage of infection
  • IgG positive was interpreted as chronic carrier
    or previous infection or reinfection.

  • In this study, 80 acute febrile illness patients
    were included and divided into 2 groups
  • - Group I 56 patients with clinical diagnosis
    of typhoid fever and
  • - Group II 24 patients of suspected
    Non-typhoidal fever.
  • Routine investigations(CBC, urine analysis and
    culture, CXR, LFTs), blood culture, widal test
    and tyhidot test were done in all patients.
  • Results of blood culture, widal, and typhidot
    test were compared in all patients for their
    sensitivity and specificity.

  • In group I Blood culture was positive in 38,
    widal test was significance in 32 typhidot
    tests were positive 44 out of 56 patients
  • In group II All were(24 patients) blood culture
    negative 4 patients (17 ) were widal
    significance , while only 3 (12 .5 ) tests were
    positive for typhidot.

Comparison of Blood culture, widal test and
Test Typhoid Cases (n 56) Group I Non-typhoidal case (n24) Group II
Blood culture 38(68) 0
widal test 32(57) 4(17)
Typhidot 44(79) 3(12.5)
Comparison of Widal test and Typhidot testsin
Culture Proven Cases and Non-Typhoid Cases.
Test Culture Positive Typhoid Cases (n 38 ) Non-Typhoid Case (n24)
Widal 24(74) 4(17)
Typhidot 35(92) 3(12.5)
On comparative evaluation of widal test, typhidot
and blood culture
  • Widal test Sensitivity- 57 and specificity -
  • Blood culture Sensitivity- 68 and
  • Typhidot test Sensitivity-79 and
  • Amongst all the 38 patients in Group I, who were
    having positive blood culture, typhidot test was
    positive in 35 patients, giving a sensitivity of
    92, a specificity of 87.5 and a positive
    predictive value of 92 as compared to widal test
    which was positive in 28 patients with a
    sensitivity, specificity, positive predictive
    value of 74, 83, and 87.5 respectively.

  • Typhoid fever is a systemic illness with a
    significant morbidity and mortality in developing
  • Poor sanitation, overcrowding, low standard of
    living, lack of medical facilities,indiscriminate
    use of antibiotics and lack of vaccination lead
    to endemicity of typhoid fever and
    multi-resistant strains of Salmonella typhi in
    developing countries.

  • Blood culture has remained the gold standard test
    in diagnosis of typhoid fever, but its utility in
    early diagnosis is limited in early phase of
    illness thereby making the isolation of the
    organism difficult.
  • Widal test has been used for over a century in
    developing countries for diagnosing typhoid fever
    but it has a low sensitivity, specificity and
    positive predictive value, which changes with the
    geographical areas.

  • Similar study carried out in the southern part of
    India reported typhidot of having a sensitivity
    of 100 and a specificity of 80
  • In another study group of typhoid patients in
    Pakistan, typhidot test had a comparable
    sensitivity of 94 and specificity of 77, while
    widal test had a sensitivity and specificity of
    63 and 83 only.

  • The effectiveness of typhidot test was also
    studied in two different studies in Malaysia. Its
    sensitivity and specificity was reported as 90.3
    and 91.9 respectively in the first study and
  • In second study, also showed a sensitivity and
    specificity of 98 and 76.6 respectively.
  • Both the Malaysian studies showed it to be a
    better test in contrast to widal test for rapid

  • Typhidot test is a highly sensitive and specific
    test in diagnosing typhoid fever.
  • It is a rapid, easy to perform, more reliable
    test for typhoid fever as compared to widal test
    and can be useful in early institution of
  • However, a larger prospective study would be
    required to fully evaluate the usefulness of this
    test in countries endemic to typhoid fever.
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