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The dilemma of widal test - which brand to use? a study of four different widal brands: a cross sectional comparative study.

Bakr WM, El Attar LA, Ashour MS, El Toukhy AM - Ann. Clin. Microbiol. Antimicrob. (2011)

Bottom Line: All samples were tested using the four different Widal brands and Salmonella Typhi IgM anti-LPS ELISA. -The results of Widal tests differed markedly using the four Widal brands in terms of sensitivity and specificity at three cut-off values of 1/80, 1/160 and 1/320.Remel brand gave the highest sensitivities and the lowest specificities and Dialab brand gave the highest specificities and the lowest sensitivities for both anti-O and anti-H antibodies at the three cut-off values.-Four fold rise in the antibodies titer was not demonstrable among clinically diagnosed typhoid fever patients-H agglutinins were less sensitive and less specific than O agglutinins -Widal test results showed marked discrepancies using different Widal brands.Raised O agglutinins were of slightly greater diagnostic value than raised H agglutinins.

View Article: PubMed Central - HTML - PubMed

Affiliation: Microbiology Department, High Institute of Public Health, Alexandria University, High Institute of Public Health, Egypt. wafaabakr@hotmail.com

ABSTRACT

Background: Serodiagnosis of typhoid fever by Widal test based on demonstrating the presence of agglutinins (antibodies) in the serum of an infected patient, against the H (flagellar) and O (somatic) antigens of Salmonella enterica serotype Typhi has been associated with many debates. This is why the aim of this study was to: (i) Compare the diagnostic accuracy of four different commercial kits used to perform Widal test (Remel, BioSystems, Dialab and Biotec). (ii) Compare the sensitivity and specificity of both anti-O and anti-H antibodies. (iii) Compare the validity of single versus paired serum samples with a rising titer for the diagnosis of typhoid fever.

Methods: Duplicate serum samples were obtained from 150 patients clinically diagnosed as typhoid fever patients. Moreover, single serum samples were obtained from 25 patients with febrile diseases other than typhoid fever. All samples were tested using the four different Widal brands and Salmonella Typhi IgM anti-LPS ELISA.

Results: -The results of Widal tests differed markedly using the four Widal brands in terms of sensitivity and specificity at three cut-off values of 1/80, 1/160 and 1/320. Remel brand gave the highest sensitivities and the lowest specificities and Dialab brand gave the highest specificities and the lowest sensitivities for both anti-O and anti-H antibodies at the three cut-off values.-Four fold rise in the antibodies titer was not demonstrable among clinically diagnosed typhoid fever patients-H agglutinins were less sensitive and less specific than O agglutinins

Conclusions: -Widal test results showed marked discrepancies using different Widal brands. None of the serum samples of the typhoid fever patients showed four fold rise in the antibody titers. Raised O agglutinins were of slightly greater diagnostic value than raised H agglutinins.

Significance and impact of study: Widal test done sequentially using two brands could be of value in typhoid fever diagnosis. Single serum sample could be used for typhoid fever diagnosis relying on anti O titer.

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Positive Widal test for anti-H antibodies.
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Figure 2: Positive Widal test for anti-H antibodies.

Mentions: - The patient's sera were serially diluted (2 fold) in normal saline, starting by 1/80 to obtain dilutions of 1/80, 1/160, 1/320, 1/640, and 1/1280. One ml of each dilution was dispensed in each of 8 tubes making two rows each of 4 tubes. For the first row of tubes a drop of anti O antibodies (of each of the four used Widal brands) was added, while to the second row of tubes a drop of anti H antibodies (of each of the four used Widal brands) was added. A tube containing 1 ml saline was included as a negative control. All tubes were mixed, O suspensions were incubated at 50°C for 4 hours and H suspensions were incubated at 50°C for 2 hours. In a positive O reaction, there was a granular agglutination; while H agglutination has a characteristic floccular appearance. In a negative reaction and in the saline the appearance of the suspension should be unchanged, and show a typical swirl when the tube is flicked. The tubes were not shaken. The titer in each case is the highest tube dilution of the serum showing agglutination. Figure 1, 2


The dilemma of widal test - which brand to use? a study of four different widal brands: a cross sectional comparative study.

Bakr WM, El Attar LA, Ashour MS, El Toukhy AM - Ann. Clin. Microbiol. Antimicrob. (2011)

Positive Widal test for anti-H antibodies.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3050682&req=5

Figure 2: Positive Widal test for anti-H antibodies.
Mentions: - The patient's sera were serially diluted (2 fold) in normal saline, starting by 1/80 to obtain dilutions of 1/80, 1/160, 1/320, 1/640, and 1/1280. One ml of each dilution was dispensed in each of 8 tubes making two rows each of 4 tubes. For the first row of tubes a drop of anti O antibodies (of each of the four used Widal brands) was added, while to the second row of tubes a drop of anti H antibodies (of each of the four used Widal brands) was added. A tube containing 1 ml saline was included as a negative control. All tubes were mixed, O suspensions were incubated at 50°C for 4 hours and H suspensions were incubated at 50°C for 2 hours. In a positive O reaction, there was a granular agglutination; while H agglutination has a characteristic floccular appearance. In a negative reaction and in the saline the appearance of the suspension should be unchanged, and show a typical swirl when the tube is flicked. The tubes were not shaken. The titer in each case is the highest tube dilution of the serum showing agglutination. Figure 1, 2

Bottom Line: All samples were tested using the four different Widal brands and Salmonella Typhi IgM anti-LPS ELISA. -The results of Widal tests differed markedly using the four Widal brands in terms of sensitivity and specificity at three cut-off values of 1/80, 1/160 and 1/320.Remel brand gave the highest sensitivities and the lowest specificities and Dialab brand gave the highest specificities and the lowest sensitivities for both anti-O and anti-H antibodies at the three cut-off values.-Four fold rise in the antibodies titer was not demonstrable among clinically diagnosed typhoid fever patients-H agglutinins were less sensitive and less specific than O agglutinins -Widal test results showed marked discrepancies using different Widal brands.Raised O agglutinins were of slightly greater diagnostic value than raised H agglutinins.

View Article: PubMed Central - HTML - PubMed

Affiliation: Microbiology Department, High Institute of Public Health, Alexandria University, High Institute of Public Health, Egypt. wafaabakr@hotmail.com

ABSTRACT

Background: Serodiagnosis of typhoid fever by Widal test based on demonstrating the presence of agglutinins (antibodies) in the serum of an infected patient, against the H (flagellar) and O (somatic) antigens of Salmonella enterica serotype Typhi has been associated with many debates. This is why the aim of this study was to: (i) Compare the diagnostic accuracy of four different commercial kits used to perform Widal test (Remel, BioSystems, Dialab and Biotec). (ii) Compare the sensitivity and specificity of both anti-O and anti-H antibodies. (iii) Compare the validity of single versus paired serum samples with a rising titer for the diagnosis of typhoid fever.

Methods: Duplicate serum samples were obtained from 150 patients clinically diagnosed as typhoid fever patients. Moreover, single serum samples were obtained from 25 patients with febrile diseases other than typhoid fever. All samples were tested using the four different Widal brands and Salmonella Typhi IgM anti-LPS ELISA.

Results: -The results of Widal tests differed markedly using the four Widal brands in terms of sensitivity and specificity at three cut-off values of 1/80, 1/160 and 1/320. Remel brand gave the highest sensitivities and the lowest specificities and Dialab brand gave the highest specificities and the lowest sensitivities for both anti-O and anti-H antibodies at the three cut-off values.-Four fold rise in the antibodies titer was not demonstrable among clinically diagnosed typhoid fever patients-H agglutinins were less sensitive and less specific than O agglutinins

Conclusions: -Widal test results showed marked discrepancies using different Widal brands. None of the serum samples of the typhoid fever patients showed four fold rise in the antibody titers. Raised O agglutinins were of slightly greater diagnostic value than raised H agglutinins.

Significance and impact of study: Widal test done sequentially using two brands could be of value in typhoid fever diagnosis. Single serum sample could be used for typhoid fever diagnosis relying on anti O titer.

Show MeSH
Related in: MedlinePlus