Enteric Fever in Patients of Lahore: Association of Positive Blood Cultures with the Typhidot Immunoassay Tests and Widal Agglutination

Abstract

Objective: Laboratory study to assess the correlation of existing Salmonella blood culture isolates with Widal agglutinin titers and EIA-based Typhidot immunoassay antibodies as the gold standard.
 Materials and Methods: This study was conducted at the department of community medicine KEMU Lahore for six months from June 2017 to November 2018. 2704 blood samples were taken for cultural studies and Widal test in a clinical laboratory among people with symptoms of clinical intestinal fever. Of these, 1497 were isolated from Salmonella; The sera of these patients who did not accompany Typhidot requests were also subjected to spot immunoassay with the informed consent required for bleeding. All sera were stored at 40 ° C until selection.
 Results: Blood of 802 men (53.6%) and 695 women (46.4%) gave 61.85% S. typhi (n = 926), 31.26% S. Para typhi-A (n = 468) and 6, 88% S. Para typhi. n = 103) insulation. Broad agglutinins were detected in 473 (31.5%) of these people. Without detectable "O" antibodies, 1:80 "H" titers (n = 264: 17.6%) were most commonly observed in children's sera (n = 112; 7.4%). Widal H with agglutinin "O" was recorded in 209 (13.9%) corresponding positive blood cultures, and 104 (6.9%) gave a titre of 1: 320 or more. A total of 1,024 sera (58.4%) did not have detectable Widal antibody. Typhidot immunoglobulin spots (57.1%), negative in 856 sera, were detected in 641 samples (42.8%). IgG-free IgM stains without detectable IgM, IgG stains without IgG were also observed in 22 sera (1.47%) and samples producing S. Para typhi-A isolate (n = 8) and S. Para typhi-B.
 Conclusion: S. Para typhi-A has often grown in the last decade, suggesting incomplete protective coverage, probably with a monovalent vaccine. Antibodies against Widal and Typhidot agglutinins were detected in the serum of patients with Salmonella growing in blood in 31.5% and 42.8%, respectively. Widal may be misinterpreted because of possible "lower" agglutinins that have not been inoculated, and the EIA immunoassay is particularly limited only to S. typhi. An ICT based Salmonella serotype three indicator is desirable.