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A comparative study of widal test with blood culture in the diagnosis of typhoid fever in
febrile patients Pembimbing :
dr. Rahmi Dewi Sp.PD
ASTRID AVIDITAH2A010007
A comparative study of widal test with blood culture in the diagnosis of typhoid fever in febrile patients
• Gizachew Andualem, Tamrat Abebe, Nigatu Kebede, Solomon Gebre-Selassie, Adane Mihret and Haile Alemayehu
• BMC Research Notes 2014, 7:653• http://www.biomedcentral.com/1756-0500/7/653
BackgroundTyphoid fever
is a systemic prolonged febrile illness caused by certain Salmonella serotypes including Salmonella typhi, S. paratyphi A , S. paratyphi B and S. paratyphiC. – Human being is the only reservoir host– Transmitted fecal-oral
• more likely to be seen in India, South and Central America, and Africa
• areas with rapid population growth, increased urbanization, and limited safe water, infrastructure, and health systems
• Diagnosis of typhoid fever– clinical signs and symptoms– serological markers– bacterial culture– antigen detection and DNA amplification – Blood, bone marrow, stool culture most reliable diagnostic
expensive, often unavailable– Widal test most widely used.
relatively cheaper, easy to perform and requires minimal training and equipment
• Widal test– the value of the test to diagnose typhoid fever has
been debated for as many years as it has been available
– It relies classically on the demonstration of a risingtiter of antibodies in paired samples 10 to 14 days apart
– such a rise is not always demonstrable, even in blood culture-confirmed cases
Interpreting the test has been such a problem that different cut offs have been reported fromn different places
patient management cannot wait for results obtained with a convalescent-phase sample a treatment decision must be made on the basis of the results obtained with a singleacute-phase sample
evaluating the result of a single Widal test is necessary for correct interpretation
This study was carried out to evaluate the value of a single acute-phase Widal test result by blood culture for thediagnosis of typhoid fever in febrile patients in St. Paul’sGeneral Specialized Hospital, Addis Ababa , Ethiopia.
Methods
• Area & periodSt. Paul’s general Specialized Hospitals, Addis Ababa, Ethiopia from December 2010 to March 2011
• Study design prospective study
• Population 277 suspected febrile patients
Blood culture
Blood sampling
Inoculation in culture medium
Biochemical screening Incubated again for 7 days, subculture before reported (-)
Widal test
Qualitative slide agglutination Semiquantitative tube agglutination (titration)
1 drop of S. O & H antigen + 1 drop serum
Rotated 100 rpm 1 min
reactive Non reactive
Serially dilute serum sample with 0,95% saline from 1/20-
1/640
+ 1 drop of S. O & H antigen
O 1/80 & > H 1/160 & >
Recent infection of typhoid
Weakly reactive
Titration test
Result
• Quantitative slide agglutination test
• Semi quantitative (titration)
• Blood culture
High antibody titer in non typhoidal infection
Conclusions
• Sensitivity 71,4 %widal test detects 71,4% of patients with typhoid fever (true positives) but 28,6% with the typhoid fever go undetected (false negatives).
• Specificity 68,44%correctly reports 68,44% of patients without TF as test negative (true negatives) but 31,6% patients without TF are incorrectly identified as test positive (false positives).
• Positive predictive value (PPV) 5,7%possibility for having typhoid fever when widal test result (+) 5,7%
• Negative predictive value (NPV) 98,9%possibility for not having typhoid fever when widal test result (-) 98,9%
• A high antibody titer development is also seen in nontyphoidal febrile infections
Using Widal test as the only laboratory test for the diagnosis of typhoid fever will result in misleading diagnosis
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