Development of Inhouse Immunoblot Method for Detection of Anti Salmonella Antibody and Comparison with Widal Test

Abstract

Enteric fever has emerged as an important infectious disease in the early 19th century. This study is carried out in search of an accurate diagnostic method enabling direct observation of antibody binding to antigen profiles, avoiding problems with non-specific antibody binding. To develop an inhouse immunoblot method for detection of anti salmonella antibody against antigens like LPS and S.typhi culture filtrates and compare with Widal in search of an accurate diagnostic assay for typhoid fever. Cross-sectional comparative study for a period of 1 year in a tertiary care hospital. 100 cases having clinical suspicion of typhoid fever and 40 controls (20 healthy persons and 20 non- typhoidal febrile patients) were studied. Subjects were investigated by blood culture, Widal test and Immunoblot and the results were compared. SPSS version 20 was used to analyze the results.Out of 100 cases 58(58%) were positive by widal and 74(74%) by immunoblot.Sensitivity and Specificity was found to be 58%, 85% for widal and 74%, 95% for Immunoblot respectively.Positive and negative predictive values were found to be 90.63%, 44.74% for widal and 97.37%, 59.38% for Immunoblot.Immunoblotting procedure incorporating Salmonella typhi culture filtrates is found to be more sensitive than the Widal agglutination assay for providing evidence of infection with Salmonella typhi.

Keywords

• immunoblot
• typhoid fever
• widal agglutination test